What is Stock/Inventory? Meaning, Importance & Examples

Welcome to Finance with Aishira 👋

Welcome to Finance with Aishira, where Commerce, Accounting, Finance, Business, and Taxation are explained in the simplest way possible. Whether you run a grocery store, clothing shop, restaurant, bakery, manufacturing business, or online store, there is one thing you need to keep track of carefully. 

Stock or Inventory : A business may purchase goods worth thousands or even lakhs of rupees, but purchasing them is only the beginning.

What is Stock or Inventory?

Stock or Inventory refers to the goods and materials that a business keeps for selling, producing goods, or supporting its business operations. In simple terms, inventory is the collection of items a business holds as part of its normal business activities.

For example: A grocery store keeps rice, flour, biscuits, oil, and other products for sale. A clothing store keeps shirts, trousers, dresses, and jackets for customers. A bakery keeps flour, sugar, butter, eggs, cakes, and pastries. A manufacturing company keeps raw materials, partly finished products, and finished goods. All of these can form part of a business's inventory depending on the nature of the business.

Simple Definition

Stock or Inventory is the collection of goods and materials held by a business for sale, production, or use in its normal business operations.

Inventory is therefore not limited to products that are already ready for sale. Depending on the type of business, it may also include materials that are still waiting to be used or products that are still being manufactured.

💡 Aishira Explains

Think of inventory as the goods and materials a business keeps available for its business activities. For a clothing shop, inventory could be clothes waiting to be sold. For a bakery, inventory could include both ingredients and finished products. For a manufacturing business, inventory could include raw materials, partially completed products, and finished goods.

So, whenever you hear the word inventory, think: "What goods or materials does this business currently have for selling or carrying out its operations?"

Stock vs Inventory — Are They the Same?

You may hear businesses use both the words Stock and Inventory. For beginners, these terms are generally used interchangeably when referring to goods held by a business.

For example:

• "The business has sufficient stock."

• "The business has sufficient inventory."

Both statements generally mean that the business has goods available for its business activities.

Simple Understanding

Stock ≈ Inventory

However, as you study advanced accounting, you may come across situations where the terminology is used more specifically. For basic Commerce and Accounting, remembering that stock and inventory are commonly used to refer to goods held by a business is sufficient.

🌍 Example

Suppose a bakery purchases:

• Flour worth ₹10,000

• Sugar worth ₹5,000

• Butter worth ₹8,000

• Chocolate worth ₹7,000

The bakery uses some of these ingredients to prepare cakes and pastries. It also has finished cakes and pastries waiting to be sold. The items held by the bakery form part of its inventory, depending on their stage and purpose. This example shows that inventory can exist in different forms within the same business.

Why is Inventory Important?

You might wonder: "Why do businesses need to maintain inventory? Can't they simply purchase goods whenever they need them?"

In theory, they could. But in practice, this can create serious problems. Imagine a restaurant suddenly runs out of essential ingredients during the lunch rush. Or a clothing shop doesn't have the popular sizes customers are asking for. Or an electronics store runs out of its best-selling smartphone. In each situation, the business could lose sales and customers. At the same time, keeping too much inventory can also be a problem.

Excess stock can:

• Tie up business money.

• Require additional storage.

• Become damaged.

• Expire.

• Become outdated.

• Increase wastage.

Therefore, businesses need to maintain an appropriate level of inventory.

Main Reasons Why Inventory is Important

A business maintains inventory for several important reasons.

1. Helps Meet Customer Demand

Customers expect products to be available when they want to purchase them. A grocery store needs products on its shelves. A clothing store needs different sizes and designs. A restaurant needs ingredients to prepare food. Maintaining sufficient inventory helps businesses satisfy customer demand.

🌍 Example

Suppose a stationery shop normally sells around 500 notebooks every month. If the shop keeps only 100 notebooks in stock and does not reorder them on time, it may run out before the month ends. Customers may then purchase notebooks from another shop. Proper inventory management helps prevent such situations.

2. Prevents Lost Sales

Running out of stock can directly affect sales. When a customer wants a product but the business doesn't have it available, the customer may choose a competitor.

This means the business can lose:

• The current sale.

• A potential repeat customer.

• Future revenue.

Therefore, maintaining adequate inventory is important for protecting sales opportunities.

3. Reduces Wastage

Too much inventory can create wastage. This is especially important for businesses dealing with perishable products.

For example:

• Milk can spoil.

• Vegetables can rot.

• Bread can become stale.

• Food products can expire.

Other products can also become outdated or lose their usefulness. Proper inventory management helps businesses avoid purchasing much more than they can actually use or sell.

4. Helps Manage Cash Flow

Inventory requires money. When a business purchases goods, cash is converted into inventory. That money remains invested in the inventory until the goods are sold or consumed.

💡 Aishira Explains

Think of it this way:

Cash

⬇️

Purchase Inventory

⬇️

Inventory Held by Business

⬇️

Inventory Sold/Used

⬇️

Revenue / Cash 

This is why businesses should avoid unnecessarily keeping large amounts of inventory. Too much inventory can lock up cash that could otherwise be used for:

• Paying suppliers.

• Paying employees.

• Paying rent.

• Purchasing equipment.

• Meeting other business expenses.

5. Supports Smooth Business Operations

Inventory is not important only for businesses that sell physical products. Many businesses need materials to continue their daily operations.

For example, a restaurant may need:

• Food ingredients.

• Packaging materials.

• Disposable containers.

• Cleaning supplies.

A manufacturing company may need:

• Raw materials.

• Components.

• Packaging materials.

Without the necessary materials, business operations may slow down or stop.

Is Inventory an Asset?

Yes. Inventory is generally classified as a Current Asset. Why? Because businesses normally expect inventory to be sold or consumed during their normal operating cycle. For example, a retailer purchases goods from suppliers and keeps them until customers purchase them. Once sold, the inventory is converted into sales and eventually cash. Therefore, inventory is generally presented under Current Assets in the Balance Sheet.

💡 Aishira Explains

A simple way to remember this is: Inventory is a Current Asset because it is normally expected to be sold or consumed during the normal operating cycle of the business.

For example: Inventory → Sale → Revenue → Cash

The inventory doesn't usually remain in the business permanently like machinery or buildings. It keeps moving through the business cycle.

Inventory in Different Types of Businesses

Inventory does not look the same in every business. Let's look at some simple examples.

Grocery Store

A grocery store may have:

• Rice

• Flour

• Sugar

• Cooking oil

• Biscuits

• Snacks

• Beverages

• Packaged food

These products are generally purchased for resale.

Clothing Store

A clothing store may have:

• Shirts

• Trousers

• Jeans

• Dresses

• Jackets

• Shoes

• Accessories

These goods remain in inventory until they are sold to customers.

Bakery

A bakery may have:

• Flour

• Sugar

• Butter

• Eggs

• Chocolate

• Cakes

• Bread

• Pastries

• Cookies

Here, inventory can include both materials used in production and finished products.

Manufacturing Business

A manufacturing business may have:

• Raw materials.

• Components.

• Partially completed products.

• Finished goods.

This makes inventory particularly important because goods can exist at different stages of production.

Common Mistakes Beginners Make

Mistake 1: Thinking Inventory Means Only Finished Goods

Inventory isn't limited to products that are ready to sell. Depending on the business, inventory may also include materials and products at different stages of production.

Mistake 2: Thinking Every Business Has the Same Inventory

A bakery doesn't maintain the same inventory as a clothing store. Inventory depends on the nature and activities of the business.

Mistake 3: Thinking More Inventory is Always Better

Having more stock doesn't automatically mean a business is doing better.

Excess inventory can:

• Tie up cash.

• Increase storage costs.

• Increase wastage.

• Become outdated.

• Increase the risk of damage.

Mistake 4: Ignoring Inventory Records

A business may have strong sales but still face problems if its inventory records are inaccurate.

Poor records can lead to:

• Stock shortages.

• Overstocking.

• Wastage.

• Incorrect inventory figures.

• Incorrect profit calculations.

🧠 Memory Trick

Remember: Inventory = Goods + Materials held for Business

Whenever you see the word Inventory, ask: "What goods or materials is the business holding for its normal business activities?"

This simple question will help you understand the concept instead of memorizing a complicated definition.

We also learned that inventory is generally treated as a Current Asset. But here's something important:

Not all inventory is in the same condition. A manufacturing business may have raw materials waiting to be used. It may also have products currently being manufactured. And it may have completed products waiting to be sold. So, how do we classify these different forms of inventory?

Let's understand them one by one.

What are the Types of Inventory?

Inventory can be classified according to its purpose and stage in the business process.

The major types we'll discuss are:

1. Raw Materials

2. Work-in-Progress (WIP)

3. Finished Goods

4. MRO Supplies

Each type plays a different role in business operations.

1. Raw Materials

Raw materials are the basic materials that a business uses to produce its goods. They have been purchased by the business but have not yet been converted into finished products.

Simple Definition

Raw materials are basic materials purchased and held for use in the production of goods.

Raw materials are especially important in manufacturing businesses.

💡 Aishira Explains

Think about making a cake. Before you have a finished cake, you need ingredients such as:

• Flour

• Sugar

• Butter

• Eggs

• Chocolate

These ingredients are the starting materials. Similarly, a manufacturing business purchases materials that will later be transformed into finished products. Those materials are called raw materials.

🌍 Example

Suppose a furniture manufacturer produces wooden tables.

The company purchases:

• Wood

• Nails

• Glue

• Paint

• Metal fittings

Before these materials are used in production, they form part of the company's raw material inventory. Once production begins, these materials move into the production process.

Raw Materials in Different Businesses

The type of raw material depends on the nature of the business.

Business	Examples of Raw Materials
Furniture manufacturer	Wood, nails, glue
Bakery	Flour, sugar, butter
Garment manufacturer	Fabric, thread, buttons
Automobile manufacturer	Steel, glass, rubber
Paper manufacturer	Pulp, chemicals

The key idea is simple: Raw materials are inputs used to make something else.

2. Work-in-Progress (WIP)

Now imagine that the raw materials have entered the production process. They are being converted into products, but the products are not yet completely finished. This stage is called Work-in-Progress, commonly abbreviated as WIP.

Simple Definition

Work-in-Progress (WIP) refers to goods that are currently undergoing production but are not yet completely finished.

💡 Aishira Explains

Think of WIP as: "Not raw anymore, but not finished yet." The production process has started. Some work has already been completed. But the final product still needs additional work before it can be sold.

🌍 Example

Suppose a furniture company is making a wooden table. The process might look like this:

Wood

⬇️

Wood cut into pieces

⬇️

Pieces assembled

⬇️

Table being polished

⬇️

Finished Table

If the table is currently being assembled or polished, it is Work-in-Progress. It isn't raw material anymore.  But it isn't a finished product either. Therefore, it is classified as WIP.

Another Example of WIP

Consider a garment manufacturing company. The company purchases fabric.

At this stage: Fabric → Raw Material The fabric is then cut and stitched.

At this stage: Partially stitched shirt → Work-in-Progress 

Once stitching, finishing, checking, and packaging are completed: Ready-to-sell shirt → Finished Goods

This gives us a very simple flow: Raw Material → WIP → Finished Goods

3. Finished Goods

Once the production process is completely finished, the resulting products are called Finished Goods.

Simple Definition

Finished goods are products that have completed the production process and are ready for sale to customers.

These products are no longer waiting for manufacturing work. They are ready to be sold.

💡 Aishira Explains

Think of finished goods as: "Ready to go to the customer." The production process is complete. The product meets the business's requirements and is ready for sale.

🌍 Example

A furniture manufacturer completes a wooden table.

The table has been:

• Cut

• Assembled

• Polished

• Inspected

• Completed

It is now ready to be sold. Therefore, the table is a Finished Good.

Examples of Finished Goods

Different businesses have different finished goods.

Business	Finished Goods
Furniture manufacturer	Tables, chairs, cupboards
Bakery	Cakes, bread, pastries
Garment manufacturer	Shirts, trousers, dresses
Automobile manufacturer	Cars, motorcycles
Electronics manufacturer	Televisions, smartphones.

The important point is that the goods are complete and ready for sale.

4. MRO Supplies

The fourth category is slightly different.

MRO stands for: Maintenance, Repair, and Operations

MRO supplies are materials used to support the business's operations, rather than being directly incorporated into the final product.

Simple Definition

MRO supplies are items used for maintaining, repairing, and operating a business but are generally not part of the finished product sold to customers.

💡 Aishira Explains

Imagine a factory. The factory produces furniture. The wood becomes part of the furniture. But the cleaning materials used to clean the factory floor don't become part of the furniture. Similarly, tools used to maintain machines may be necessary for production, but they don't become part of the final product. These supporting items can be considered MRO supplies.

🌍 Examples of MRO Supplies

MRO supplies may include:

• Cleaning materials

• Lubricants

• Maintenance tools

• Safety equipment

• Gloves

• Repair materials

• Certain office or operational supplies

Their main purpose is to keep the business operating properly.

Raw Materials vs WIP vs Finished Goods

These three types can be confusing at first.

So let's compare them.

Type	Stage	Meaning
Raw Materials	Before production	Materials waiting to be used
WIP	During production	Products currently being made
Finished Goods	After production	Completed products ready for sale

🧠 Easy Memory Trick

Remember: RAW → WORKING → READY

RAW = Raw Materials

WORKING = Work-in-Progress

READY = Finished Goods

This simple sequence can help you remember the production flow.

Understanding the Complete Inventory Cycle

Let's put everything together. Suppose a company manufactures wooden chairs.

Step 1: Raw Materials

The company purchases:

• Wood

• Nails

• Glue

• Paint

These are Raw Materials.

⬇️

Step 2: Production Begins

The wood is cut and assembled. The chair is partly completed. This is Work-in-Progress.

⬇️

Step 3: Production is Completed

The chair is painted, polished, inspected, and completed. It is now a Finished Good.

⬇️

Step 4: Sale

The finished chair is sold to a customer. The inventory leaves the business through the sale. So the basic inventory flow is: Raw Materials → Work-in-Progress → Finished Goods → Sale

Where Do MRO Supplies Fit?

MRO supplies are slightly different. They don't necessarily move through the same production sequence.

For example: A factory uses lubricant to maintain a machine. The lubricant helps keep the machine working, but it does not become part of the finished chair.

So: Raw Materials → WIP → Finished Goods represents the main production inventory flow. MRO supplies, on the other hand, support the business operations.

Real-Life Example: Bakery

Let's understand the different types through a bakery.

Suppose a bakery produces cakes.

Raw Materials

The bakery purchases:

• Flour

• Sugar

• Eggs

• Butter

• Chocolate

These are inputs for production.

→ Raw Materials

Work-in-Progress

The ingredients are mixed and the cake is being prepared and baked. The cake is not yet ready for customers. → Work-in-Progress

Finished Goods

The cake has been completely baked, decorated, checked, and is ready for sale. → Finished Goods

MRO Supplies

The bakery also uses:

• Cleaning supplies

• Maintenance materials

• Gloves

• Certain equipment-related supplies

These support the bakery's operations. → MRO Supplies

Real-Life Example: Clothing Manufacturer

Let's take another example. A clothing manufacturer produces shirts.

Raw Materials

• Fabric

• Thread

• Buttons

• Zippers

→ Raw Materials

Work-in-Progress

The fabric has been cut and the shirt is being stitched. → WIP

Finished Goods

The shirt has been stitched, finished, checked, and packed. → Finished Goods

MRO Supplies

The factory may use:

• Machine maintenance materials

• Cleaning supplies

• Lubricants

• Safety equipment

→ MRO Supplies . Again, the same concept applies.

Why is Classifying Inventory Important?

You may wonder: "Why do we need different categories? Can't we just call everything inventory?"
Businesses classify inventory because different items have different purposes and stages.

Proper classification helps businesses:

• Track materials properly.

• Monitor production.

• Identify completed products.

• Plan purchases.

• Control stock levels.

• Calculate inventory more accurately.

• Manage business operations efficiently.

For a manufacturing business, knowing how much raw material is available is very different from knowing how many finished products are ready for sale.

Common Mistakes

Mistake 1: Confusing Raw Materials with Finished Goods

Raw materials are inputs. Finished goods are completed products. They are opposite ends of the production process.

Mistake 2: Thinking WIP Means Damaged Goods

Work-in-Progress does not mean damaged or defective products. It simply means the product is still being manufactured or processed.

Mistake 3: Thinking Every Business Has WIP

Not every business necessarily has WIP. A retailer that simply purchases finished products and resells them may not have a manufacturing WIP stage. WIP is particularly relevant to businesses involved in production or processing.

Mistake 4: Thinking MRO Supplies Become Part of the Product

MRO supplies support business operations. They generally don't become part of the finished product sold to customers.

🧠 Memory Trick

Remember the four types like this:

R → W → F + M

R = Raw Materials
W = Work-in-Progress
F = Finished Goods
M = MRO Supplies

Or remember:

Start → Process → Finish + Support

Start: Raw Materials

Process: WIP

Finish: Finished Goods

Support: MRO Supplies

Inventory Valuation: Meaning, Methods, COGS & Profit Explained

Welcome to Finance with Aishira 👋

In the previous parts, we learned what Stock/Inventory means and explored its major types:

• Raw Materials

• Work-in-Progress (WIP)

• Finished Goods

• MRO Supplies

But knowing how much inventory a business has is only half the story.

There's another important question:

How much is that inventory worth?

Imagine a business purchases goods several times during the year.

The prices may not always be the same.

For example:

• January: 100 units at ₹10 each

• March: 100 units at ₹12 each

• June: 100 units at ₹15 each

Now suppose 150 units are sold.

How should the business determine the cost of the 150 units sold?

And how much value should be assigned to the 150 units still remaining?

This is where Inventory Valuation becomes important.

What is Inventory Valuation?

Inventory valuation means determining the monetary value of the inventory held by a business at the end of an accounting period.

Simple Definition

Inventory valuation is the process of assigning a monetary value to the inventory remaining with a business at the end of an accounting period.

In simple words:

Inventory valuation tells us how much the remaining stock is worth for accounting purposes.

---

💡 Aishira Explains

Suppose a shop has 100 notebooks remaining at the end of the year.

You cannot simply write:

"Closing Inventory = 100 notebooks."

Accounting needs a monetary amount.

So, the business needs to determine something like:

100 notebooks × applicable cost = ₹5,000

That ₹5,000 becomes the value assigned to the closing inventory.

This value is important because it affects the financial statements and the calculation of profit.

---

What is Closing Inventory?

Before going further, let's understand an important term:

Closing Inventory.

Simple Definition

Closing inventory is the inventory remaining unsold or unused at the end of an accounting period.

For example, suppose a business starts the year with 200 units.

During the year, it purchases another 800 units.

It sells 750 units.

The remaining:

200 + 800 − 750 = 250 units

are the closing inventory, assuming there are no other adjustments.

These 250 units need to be valued.

---

Why is Inventory Valuation Important?

You might wonder:

"Why does the value of closing inventory matter so much?"

Because inventory valuation affects the calculation of Cost of Goods Sold (COGS) and therefore affects profit.

It also affects the amount of inventory shown as an asset in the Balance Sheet.

So, inventory valuation has an impact on two important areas:

Income Statement

It affects the calculation of profit.

Balance Sheet

It affects the value of closing inventory shown as a current asset.

---

Inventory and Cost of Goods Sold (COGS)

To understand inventory valuation properly, you need to know about Cost of Goods Sold, commonly called COGS.

COGS represents the cost associated with the goods that have been sold during the accounting period.

A basic formula is:

COGS = Opening Inventory + Purchases − Closing Inventory

Let's understand this with a simple example.

🌍 Example

Suppose a business has:

• Opening Inventory = ₹20,000

• Purchases = ₹80,000

• Closing Inventory = ₹30,000

Then:

COGS = ₹20,000 + ₹80,000 − ₹30,000

COGS = ₹70,000

So, the cost of goods sold is ₹70,000.

---

Why Does Closing Inventory Reduce COGS?

This is an important point.

Suppose a business has ₹1,00,000 worth of goods available during the year.

But ₹20,000 worth of goods remain unsold at the end.

Those ₹20,000 worth of goods have not been sold yet.

Therefore, their cost should not be included in the cost of goods sold for the current period.

That's why closing inventory is deducted.

💡 Aishira Explains

Think of it this way:

You have:

₹1,00,000 worth of goods available

But:

₹20,000 is still sitting in your shop

So only:

₹80,000 worth of goods

has been treated as sold.

Therefore:

COGS = Goods Available − Closing Inventory

---

How Does Inventory Affect Profit?

Inventory valuation can affect reported profit.

The basic relationship is:

Gross Profit = Sales − COGS

And because COGS depends partly on closing inventory, the value assigned to closing inventory can affect gross profit.

🌍 Example

Suppose:

Sales = ₹1,00,000

COGS = ₹60,000

Then:

Gross Profit = ₹1,00,000 − ₹60,000

Gross Profit = ₹40,000

If the closing inventory figure changes, the COGS figure can also change, which can affect gross profit.

This is why inventory valuation needs to be done carefully and consistently.

---

Basic Inventory Valuation Methods

When inventory is purchased at different prices, businesses need a systematic method to determine the cost assigned to inventory.

Common methods include:

1. FIFO — First-In, First-Out

2. Weighted Average Cost Method

Let's understand them.

---

1. FIFO Method

FIFO stands for:

First-In, First-Out

The basic assumption is that the goods purchased first are issued or sold first.

Simple Definition

Under FIFO, the earliest purchased inventory is assumed to be sold or issued first.

💡 Aishira Explains

Imagine you have a shelf of milk cartons.

You don't want the older cartons to remain behind while newer cartons are sold first.

So, you use the older stock first.

That's the basic idea behind FIFO.

First purchased → First sold

Therefore, the inventory left at the end generally consists of the more recently purchased units.

---

🌍 FIFO Example

Suppose a business purchases:

Purchase	Quantity	Cost per Unit
First purchase	100 units	₹10
Second purchase	100 units	₹12

Total inventory: 200 units

Suppose the business sells 120 units.

Under FIFO: The first 100 units are considered sold first. Then another 20 units are taken from the second purchase.

So: 100 × ₹10 = ₹1,000

20 × ₹12 = ₹240

Therefore: COGS = ₹1,240

The remaining inventory is: 80 units × ₹12 = ₹960

So: Closing Inventory = ₹960

2. Weighted Average Cost Method

Under the Weighted Average Cost Method, inventory is valued using an average cost per unit.

Simple Definition

The weighted average method calculates an average cost per unit and uses that average to value inventory and determine the cost of goods sold.

The average is based on the total cost and total quantity available.

Formula = Weighted Average Cost per Unit = Total Cost of Inventory Available ÷ Total Units Available

🌍 Weighted Average Example

Suppose a business purchases:

Purchase	Quantity	Cost per Unit	Total Cost
First purchase	100 units	₹10	₹1,000
Second purchase	100 units	₹12	₹1,200
Total	200 units		₹2,200

Weighted average cost per unit: ₹2,200 ÷ 200 = ₹11 per unit

Therefore, the average cost of each unit is ₹11.

If the business sells 120 units: 120 × ₹11 = ₹1,320

So: COGS = ₹1,320

The remaining 80 units would be valued at: 80 × ₹11 = ₹880

Therefore: Closing Inventory = ₹880

FIFO vs Weighted Average

Let's compare the two methods.

Basis	FIFO	Weighted Average
Meaning	First purchases are assumed sold first	Average cost is used
Cost assigned to sales	Based on earlier costs first	Based on average cost
Ending inventory	Generally reflects more recent purchase costs	Reflects average cost
Calculation	Tracks purchase layers	Calculates average unit cost

🧠 Memory Trick

Remember:

FIFO = First In → First Out

Weighted Average = All Costs → One Average

Why Can Different Methods Give Different Results?

Suppose prices are changing over time. If the purchase price increases, the cost assigned to goods sold can differ depending on the method used. As a result, different inventory valuation methods may produce different figures for:

• COGS

• Closing Inventory

• Gross Profit

This is why businesses need to follow an appropriate and consistent inventory valuation policy.

Inventory Valuation and the Balance Sheet

Closing inventory is generally shown as a Current Asset in the Balance Sheet.

For example, suppose a business calculates its closing inventory as: ₹75,000

The Balance Sheet may show inventory under Current Assets at the applicable amount. Therefore, inventory valuation affects not only profit but also the financial position presented by the business.

Inventory Valuation and the Income Statement

Inventory also affects the Income Statement through COGS.

Remember: COGS = Opening Inventory + Purchases − Closing Inventory

Then: Gross Profit = Sales − COGS

So, closing inventory affects COGS.  COGS affects gross profit. 

Therefore: Inventory Valuation → COGS → Gross Profit

This is an important relationship to remember.

Common Mistakes

Mistake 1: Thinking Closing Inventory Means Purchases Made at the End

Closing inventory does not simply mean the goods purchased at the end of the year. It means the inventory remaining unsold or unused at the end of the accounting period.

Mistake 2: Thinking COGS Includes All Purchases

COGS does not simply equal total purchases. The basic formula also considers:

• Opening Inventory

• Closing Inventory

COGS = Opening Inventory + Purchases − Closing Inventory

Mistake 3: Thinking Inventory Valuation Only Affects the Balance Sheet

Inventory valuation also affects COGS and profit. Therefore, it has an impact on both the Balance Sheet and Income Statement.

Mistake 4: Confusing FIFO with LIFO

FIFO means: First-In, First-Out.  Don't reverse the words. The first inventory purchased is assumed to be sold or issued first.

🧠 Memory Trick

Remember the basic inventory formula:

Opening + Purchases − Closing = COGS

Or simply: What you had ➕ What you bought ➖What you still have = What was sold

This makes the formula much easier to understand.

But there's another important question. How does a business actually manage all this inventory?

Imagine a business that has thousands of products stored in a warehouse. If the business doesn't know:

• How much stock it has,

• Which products are selling quickly,

• Which products are sitting unsold,

• When to purchase more,

• Or which goods are damaged,

then even a profitable business can face serious problems. This is why businesses need Inventory Management.

What is Inventory Management?

Inventory management is the process of monitoring, controlling, and managing the inventory of a business.

Simple Definition = Inventory management is the process of maintaining the right quantity of inventory at the right time while controlling its cost and availability.

In simple words: Inventory management means making sure a business has enough stock when it needs it — without keeping unnecessarily large amounts of stock.

💡 Aishira Explains

Think about a stationery shop. Suppose the shop normally sells 1,000 notebooks every month. If the owner keeps only 100 notebooks, the shop may run out of stock quickly. But if the owner purchases 20,000 notebooks, a huge amount of money may remain tied up in unsold inventory. Neither situation is ideal. The goal is to find a balance. Enough inventory to meet demand + not so much that money is unnecessarily tied up. That's the basic idea behind inventory management.

What is Stock Control?

Stock control is closely related to inventory management. It involves monitoring the quantity and movement of stock so that the business knows:

• What it has.

• What has been sold.

• What has been purchased.

• What needs to be reordered.

• What is damaged or missing.

Simple Definition

Stock control is the systematic monitoring and management of the quantity and movement of inventory held by a business.

Stock control helps a business avoid both stock shortages and excess stock.

Why is Inventory Management Important?

Good inventory management can help a business operate more efficiently. Let's understand the major benefits.

1. Prevents Stockouts 

A stockout occurs when a business runs out of a product or material that is needed. For example, a restaurant may run out of a popular ingredient. A clothing shop may run out of a popular size. A manufacturer may run out of an essential raw material.

Stockouts can result in:

• Lost sales.

• Delayed production.

• Unhappy customers.

• Emergency purchases.

Proper inventory management helps reduce the risk of stockouts.

2. Prevents Overstocking

The opposite problem is overstocking. Overstocking occurs when a business holds more inventory than it reasonably needs. Suppose a store normally sells 500 units of a product every month. If it purchases 10,000 units without a reasonable reason, it may have far more stock than it can sell quickly. This can create several problems.

Overstocking may lead to:

• Money being tied up.

• Higher storage costs.

• Increased risk of damage.

• Expiry of products.

• Obsolete inventory.

• Lower cash availability.

Overstocking vs Understocking

These two terms are important.

Overstocking	Understocking
Too much inventory	Too little inventory
Cash gets tied up	Sales may be lost
Storage costs may increase	Stockouts may occur
Risk of damage or expiry increases	Customers may go elsewhere
Unsold inventory may accumulate	Production may stop

🧠 Easy Memory Trick

Remember:

Overstock = Too Much

Understock = Too Little

The goal is to maintain an appropriate stock level.

3. Helps Reduce Storage Costs

Inventory requires space. A business may need:

• Warehouses.

• Shelves.

• Refrigeration.

• Security.

• Handling equipment.

• Insurance.

The more inventory a business stores, the greater its storage requirements may become. Proper inventory management can help businesses avoid unnecessary storage expenses.

4. Reduces Wastage and Damage

Some inventory can deteriorate over time.

For example:

• Food can spoil.

• Medicines can expire.

• Electronics can become outdated.

• Fashion products can go out of style.

Proper inventory management helps businesses identify such items early and take appropriate action.

5. Improves Cash Flow

Inventory requires investment. When a business purchases large quantities of goods, cash is converted into inventory. If those goods remain unsold for a long time, the money remains tied up. Effective inventory management helps businesses avoid unnecessarily locking large amounts of cash in stock.

💡 Aishira Explains

Remember: Unsold inventory = Money still tied up in goods

The faster appropriate inventory moves through the business, the sooner the business can recover the money invested in it.

What is Stock Turnover?

Another useful concept in inventory management is Stock Turnover, also known as Inventory Turnover. It measures how many times inventory is sold or used and replaced during a particular period.

Simple Definition

Inventory turnover measures how quickly a business sells and replaces its inventory during a given period.

A business with fast-moving inventory generally sells and replaces its stock more frequently than a business with slow-moving inventory.

🌍 Example

Suppose a business has inventory that is sold and replaced several times during the year. This indicates that the inventory is moving relatively quickly. Now imagine another business whose products remain in storage for a very long time before being sold. Its inventory is moving more slowly. This information can help management understand how efficiently inventory is being managed.

Basic Inventory Turnover Formula

A commonly used formula is: Inventory Turnover Ratio = Cost of Goods Sold ÷ Average Inventory

Where: Average Inventory = (Opening Inventory + Closing Inventory) ÷ 2

🌍 Example

Suppose:

Cost of Goods Sold = ₹4,00,000

Opening Inventory = ₹60,000

Closing Inventory = ₹40,000

First calculate average inventory:

Average Inventory = (₹60,000 + ₹40,000) ÷ 2

Average Inventory = ₹50,000

Now: Inventory Turnover Ratio = ₹4,00,000 ÷ ₹50,000

Inventory Turnover Ratio = 8 times

This means the inventory was turned over approximately 8 times during the period.

What Does a High Inventory Turnover Mean?

A relatively high inventory turnover may indicate that inventory is being sold or used quickly.

This can be a positive sign because:

• Goods are moving.

• Less money may remain tied up in inventory.

• Storage requirements may be lower.

However, a very high turnover isn't automatically good. If inventory is moving extremely quickly because the business keeps too little stock, it could also experience frequent stockouts. So inventory turnover needs to be interpreted in context.

What Does a Low Inventory Turnover Mean?

A relatively low inventory turnover may indicate that goods are moving slowly. This can happen because:

• Demand is weak.

• The business purchased too much inventory.

• Products have become outdated.

• Prices are too high.

• Customers prefer other products.

Slow-moving inventory should be monitored carefully.

What is Reorder Level?

Businesses also need to know when to purchase more inventory. This is where the idea of a reorder level becomes useful.

Simple Definition

Reorder level is the inventory level at which a business should place a new order to replenish its stock before it runs out.

🌍 Example

Suppose a business notices that its stock of a particular product falls to around 100 units. Based on its normal sales and supplier delivery time, it decides that 100 units should be the point at which it places a new order.

So: Reorder Level = 100 units

Once inventory reaches this level, the business places a new purchase order.

Why is Reorder Level Important?

Without a proper reorder system, a business may realize that stock is running low only when it is almost finished. By then, it may be too late.

A proper reorder level helps the business:

• Avoid stockouts.

• Plan purchases.

• Maintain smooth operations.

• Meet customer demand.

• Reduce emergency purchasing.

What is Safety Stock?

Businesses sometimes maintain additional inventory as a precaution. This is called Safety Stock or Buffer Stock.

Simple Definition

Safety stock is additional inventory kept to protect against unexpected increases in demand or delays in supply.

🌍 Example

Suppose a shop normally sells 50 units of a product every week. But during a festival season, demand can suddenly increase. The supplier may also take longer than usual to deliver new stock. The business may therefore keep some extra units as a safety buffer. This additional inventory is called safety stock.

Inventory Management Methods

Businesses can use different systems and techniques to manage inventory. Some common approaches include:

1. Regular Stock Counting

Businesses physically count inventory at regular intervals. This helps compare: Actual Stock  with

Recorded Stock = Any difference can then be investigated.

2. Inventory Records

Businesses maintain records showing:

• Purchases.

• Sales.

• Stock received.

• Stock issued.

• Closing inventory.

These records help management monitor inventory levels.

3. Barcode and Technology Systems

Many modern businesses use:

• Barcodes.

• QR codes.

• Inventory management software.

• Point-of-sale systems.

These systems can automatically update inventory when products are purchased or sold.

4. ABC Analysis

Businesses may classify inventory according to its importance or value. A simple ABC approach is:

A Items = High-value or highly important items that require close monitoring.

B Items = Moderately important items.

C Items = Lower-value items that may require relatively less intensive monitoring. This allows businesses to focus more attention on the inventory that matters most.

Common Mistakes

Mistake 1: Thinking More Inventory is Always Better

More inventory isn't automatically better. Excess inventory can tie up cash and increase storage and wastage risks.

Mistake 2: Waiting Until Stock is Finished to Reorder

If a business waits until inventory reaches zero, it may face stockouts. Businesses should plan their reorder points in advance.

Mistake 3: Ignoring Slow-Moving Inventory

Some products may remain unsold for months. Businesses should identify slow-moving inventory and understand why it isn't selling.

Mistake 4: Relying Only on Accounting Records

Recorded inventory and physical inventory may sometimes differ. Regular physical stock checks can help identify:

• Damage.

• Theft.

• Recording errors.

• Missing goods.

• Counting mistakes.

🧠 Memory Trick

Remember the basic goal of inventory management: Right Product + Right Quantity + Right Time + Right Cost

A business wants inventory to be: Available when needed without Unnecessarily tying up money.

What is Inventory Accounting?

Inventory accounting refers to the process of recording, tracking, and reporting transactions related to the goods and materials held by a business.

Simple Definition

Inventory accounting is the process of recording purchases, sales, returns, adjustments, and the value of inventory in the accounting records.

In simple words: Inventory accounting keeps track of what the business buys, sells, returns, uses, and still has.

💡 Aishira Explains

Think of inventory as a moving part of the business. Goods enter the business when they are purchased. Some goods leave when they are sold. Some may go back to suppliers as purchase returns. Some customers may return goods. Some goods may be damaged or lost. Accounting records help the business keep track of all these movements.

Purchase of Inventory for Cash

Suppose a business purchases goods worth ₹10,000 for cash. The business receives goods and pays cash.

The journal entry is:

Journal Entry:

Purchases A/c        Dr.   ₹10,000
      To Cash A/c                 ₹10,000

Explanation

• Purchases A/c is debited because goods are purchased.

• Cash A/c is credited because cash goes out of the business.

💡 Aishira Explains

Remember: Cash Purchase = Goods Come In + Cash Goes Out

Therefore: Purchases → Debit ; Cash → Credit

Purchase of Inventory on Credit

Now suppose the business purchases goods worth ₹25,000 on credit from ABC Traders. The business receives the goods but does not pay immediately.

The journal entry is:

Purchases A/c        Dr.   ₹25,000
      To ABC Traders A/c          ₹25,000

Explanation

• Purchases A/c is debited.

• The supplier becomes a creditor, so the supplier's account is credited.

Simple Understanding

Credit Purchase = Goods Come In + Liability is Created

The business now owes ₹25,000 to ABC Traders.

Cash Sale of Inventory

Now suppose the business sells goods for ₹15,000 for cash. The business receives cash from the customer.

The journal entry is:

Cash A/c             Dr.   ₹15,000
      To Sales A/c                ₹15,000

Explanation

• Cash increases, so Cash A/c is debited.

• Sales represent revenue, so Sales A/c is credited.

💡 Aishira Explains

Remember: Cash Sale = Cash Comes In + Sales Revenue is Earned

Therefore: Cash → Debit ; Sales → Credit

Credit Sale of Inventory

Suppose goods worth ₹20,000 are sold on credit to XYZ Ltd. The customer doesn't pay immediately.

The journal entry is:

XYZ Ltd. A/c        Dr.   ₹20,000
      To Sales A/c                ₹20,000

Explanation

• XYZ Ltd. becomes a debtor because the customer owes money.

• Sales revenue is credited.

So: Credit Sale = Customer Becomes Debtor + Sales Revenue

Purchase Return

Sometimes a business purchases goods that are:

• Damaged

• Defective

• Incorrect

• Different from what was ordered

The business may return those goods to the supplier. This is called a Purchase Return. It is also known as Returns Outward.

🌍 Example

Suppose a business purchased goods worth ₹5,000 from ABC Traders. Later, goods worth ₹1,000 are found to be defective and are returned.

The journal entry is:

ABC Traders A/c     Dr.   ₹1,000
      To Purchase Returns A/c       ₹1,000

Explanation

The amount payable to the supplier decreases. Therefore, ABC Traders' account is debited. Purchase Returns is credited.

Sales Return

Now imagine a customer purchases goods from the business but later returns some of them. This is called a Sales Return. It is also known as Returns Inward.

🌍 Example

Suppose goods worth ₹2,000 are sold to a customer. The customer later returns goods worth ₹500 because they are defective.

The journal entry is:

Sales Returns A/c   Dr.   ₹500
      To Customer A/c              ₹500

Explanation

• Sales Returns is debited.

• The amount receivable from the customer decreases.

Purchase Return vs Sales Return

These two are commonly confused by beginners.

Basis	Purchase Return	Sales Return
Meaning	Goods returned to supplier	Goods returned by customer
Also called	Returns Outward	Returns Inward
Direction	Business → Supplier	Customer → Business
Effect	Reduces purchases	Reduces sales

🧠 Memory Trick

Remember: Purchase Return = We return goods ; Sales Return = Customer returns goods

What Happens When Inventory is Sold?

This is where inventory accounting becomes slightly more interesting. Suppose a business purchased goods for ₹10,000. It later sells those goods for ₹15,000. There are two different values involved:

Cost of Goods

The business originally paid: ₹10,000

Selling Price

The customer paid: ₹15,000

The difference is: ₹15,000 − ₹10,000 = ₹5,000

This represents the gross profit on the transaction before considering other related expenses.

Sales Price vs Cost Price

This distinction is extremely important.

Cost Price = What the business paid for the goods

Selling Price = What the customer paid for the goods

For example: Cost Price = ₹10,000 ; Selling Price = ₹15,000

Therefore: Gross Profit = ₹5,000

If: Cost Price = ₹10,000 ; Selling Price = ₹8,000

then: Gross Loss = ₹2,000

Inventory and Closing Stock

At the end of an accounting period, some purchased goods may remain unsold. These goods are called Closing Inventory or Closing Stock. For example: A business purchases goods worth ₹1,00,000 during the year. At the end of the year, goods worth ₹30,000 remain unsold. That ₹30,000 represents the closing inventory, subject to the applicable inventory valuation rules.

Why is Closing Inventory Important?

Closing inventory affects the calculation of Cost of Goods Sold.

Remember: COGS = Opening Inventory + Purchases − Closing Inventory

Suppose:

• Opening Inventory = ₹20,000

• Purchases = ₹80,000

• Closing Inventory = ₹25,000

Then: COGS = ₹20,000 + ₹80,000 − ₹25,000 ; COGS = ₹75,000

This means the cost associated with the goods sold during the period is ₹75,000.

Closing Inventory and Profit

Suppose:  Sales = ₹1,20,000 ; COGS = ₹75,000

Then: Gross Profit = Sales − COGS

Gross Profit = ₹1,20,000 − ₹75,000 ; Gross Profit = ₹45,000

This shows why closing inventory matters. Closing inventory affects COGS. COGS affects gross profit.

Therefore: Closing Inventory → COGS → Gross Profit

Inventory Adjustments

Inventory may not always remain exactly as recorded.

Sometimes businesses discover:

• Damaged goods

• Missing goods

• Expired goods

• Obsolete inventory

• Differences between physical stock and accounting records

Such situations may require appropriate accounting adjustments. The exact accounting treatment depends on the nature of the adjustment and the applicable accounting framework. The important point for beginners is: Inventory records should be compared with actual physical inventory and differences should be investigated and properly accounted for.

Physical Inventory Count

Businesses often conduct a physical inventory count. This means actually counting or checking the goods available. For example, the accounting records may show: 1,000 units. But the physical count may show: 980 units. There is a difference of: 20 units. The business should investigate why the difference exists. Possible reasons may include:

• Damage

• Theft

• Recording errors

• Counting mistakes

• Unrecorded sales

• Unrecorded purchases

Inventory Records

Businesses may maintain detailed inventory records showing:

• Opening stock

• Purchases

• Sales

• Purchase returns

• Sales returns

• Stock issued or consumed

• Closing stock

• Adjustments

Modern businesses may use accounting software or inventory management systems to track these movements. For businesses with large quantities of inventory, technology can make inventory monitoring much easier.

A Simple Inventory Accounting Flow

Let's put everything together.

Step 1: Purchase Goods

Purchases

⬇️

Inventory enters the business.

Step 2: Store the Goods

Inventory remains available for sale or use.

Step 3: Sell the Goods

Sales

⬇️

Inventory leaves the business through sale.

Step 4: Handle Returns

Goods may be:

• Returned to suppliers

• Returned by customers

Step 5: Count Remaining Inventory

At the end of the accounting period, the business determines its closing inventory.

Step 6: Calculate COGS = Opening Inventory + Purchases − Closing Inventory = COGS

Step 7: Calculate Gross Profit = Sales − COGS = Gross Profit

Quick Journal Entry Summary

Here's a simple revision table.

Transaction	Debit	Credit
Cash Purchase	Purchases A/c	Cash A/c
Credit Purchase	Purchases A/c	Supplier A/c
Cash Sale	Cash A/c	Sales A/c
Credit Sale	Customer A/c	Sales A/c
Purchase Return	Supplier A/c	Purchase Returns A/c
Sales Return	Sales Returns A/c	Customer A/c

🧠 Memory Trick

Remember the basic pattern:

Purchase → Purchases A/c Dr.

Sale → Sales A/c Cr.

Purchase Return → Purchase Returns A/c Cr.

Sales Return → Sales Returns A/c Dr.

Common Mistakes

Mistake 1: Confusing Purchase Return with Sales Return

Always ask: Who is returning the goods?

If we return goods to the supplier → Purchase Return.

If the customer returns goods to us → Sales Return.

Mistake 2: Confusing Cost Price with Selling Price

The amount paid by the business and the amount received from the customer are not necessarily the same. Cost Price ≠ Selling Price

Mistake 3: Forgetting Closing Inventory in COGS

Remember: COGS = Opening Inventory + Purchases − Closing Inventory

Closing inventory is deducted because those goods have not yet been sold.

Mistake 4: Assuming Book Stock is Always Correct

Accounting records may sometimes differ from physical stock. That's why businesses should conduct physical stock counts and investigate differences.

🧠 Memory Trick

For the entire inventory accounting process, remember: BUY → HOLD → SELL → RETURN → COUNT → VALUE

BUY goods.

HOLD inventory.

SELL goods.

RETURN goods when necessary.

COUNT remaining inventory.

VALUE the closing inventory.

This gives you a simple picture of the inventory cycle.

Periodic vs Perpetual Inventory System: Meaning, Differences & Journal Entries

But there is an important question: How does a business keep track of its inventory throughout the year? Imagine a large supermarket selling hundreds of products every day. If the business had to physically count every product after every sale, it would be extremely difficult. That's why businesses use different inventory systems to track their stock.

The two major systems are:

1. Periodic Inventory System

2. Perpetual Inventory System

Let's understand both in simple terms.

What is an Inventory System?

An inventory system is the method a business uses to record, monitor, and determine the quantity and value of its inventory.

Simple Definition

An inventory system is a system used by a business to track purchases, sales, stock levels, and inventory value.

The two commonly discussed systems are Periodic and Perpetual.

What is the Periodic Inventory System?

Under the Periodic Inventory System, inventory records are not continuously updated after every purchase or sale. Instead, the business determines its inventory at specific intervals, usually through a physical stock count.

Simple Definition

A periodic inventory system is a system in which inventory is determined at regular intervals rather than being continuously updated after every transaction.

💡 Aishira Explains

Think of a small shop. The owner may record purchases and sales during the month. But instead of updating the exact inventory balance after every transaction, the owner physically counts the remaining stock at the end of the month or accounting period. That physical count helps determine the closing inventory.

So the basic idea is: Record transactions → Count inventory periodically → Determine closing stock

🌍 Example of Periodic Inventory System

Suppose a shop begins the month with: 100 units. During the month, it purchases: 500 units. At the end of the month, the owner physically counts: 150 units. The business can use these figures to determine how many units were sold or otherwise removed from inventory, subject to relevant adjustments. The key point is that the exact inventory balance was determined through a physical count at the end of the period.

How is COGS Calculated Under the Periodic System?

Under the periodic system, Cost of Goods Sold is generally determined at the end of the accounting period.

The basic formula is: COGS = Opening Inventory + Net Purchases − Closing Inventory

Where: Net Purchases = Purchases + Direct Purchase Expenses − Purchase Returns

For a basic example, suppose:

• Opening Inventory = ₹20,000

• Purchases = ₹80,000

• Purchase Returns = ₹5,000

• Closing Inventory = ₹25,000

First: Net Purchases = ₹80,000 − ₹5,000 = ₹75,000

Then: COGS = ₹20,000 + ₹75,000 − ₹25,000  = ₹70,000

Journal Entries Under the Periodic Inventory System

Under the periodic system, purchases and sales are generally recorded in separate accounts.

For example:

Cash Purchase

Purchases A/c        Dr.
      To Cash A/c

Credit Purchase

Purchases A/c        Dr.
      To Supplier A/c

Cash Sale

Cash A/c             Dr.
      To Sales A/c

Credit Sale

Customer A/c         Dr.
      To Sales A/c

Notice something important:

The basic purchase and sales entries do not continuously update the inventory account in the same way as a perpetual system. The actual closing inventory is determined through a physical count and appropriate period-end accounting adjustments.

What is the Perpetual Inventory System?

Now let's look at the second system. Under the Perpetual Inventory System, inventory records are updated continuously as purchases and sales take place.

Simple Definition

A perpetual inventory system is a system in which inventory records are continuously updated whenever inventory is purchased, sold, or otherwise changes.

💡 Aishira Explains

Imagine a modern supermarket. A customer buys one packet of coffee. The point-of-sale system records the sale. The inventory record can automatically reduce the quantity of coffee available. If another shipment arrives, the inventory record can increase. So the business can have a much more up-to-date picture of its inventory.

That's why it is called: Perpetual = Continuous

🌍 Example of Perpetual Inventory System

Suppose a store has: 100 units. A customer buys: 10 units. Under a perpetual system, the inventory record can immediately show: 100 − 10 = 90 units. Then the store receives another: 50 units. The inventory record can become: 90 + 50 = 140 units. The inventory balance keeps changing as transactions occur.

Journal Entries Under the Perpetual System

Under a perpetual system, inventory itself is updated as purchases and sales occur.

Purchase of Inventory

Suppose goods worth ₹10,000 are purchased for cash.

Inventory A/c       Dr.   ₹10,000
      To Cash A/c                 ₹10,000

The Inventory Account is debited because inventory increases.

Sale of Inventory Under the Perpetual System

This is where an important difference appears. Suppose goods that originally cost the business ₹6,000 are sold for ₹9,000. Under the perpetual system, the sale generally requires two accounting entries.

Entry 1: Record the Sale

Cash/Customer A/c   Dr.   ₹9,000
      To Sales A/c                ₹9,000

Entry 2: Record the Cost of Goods Sold

COGS A/c            Dr.   ₹6,000
      To Inventory A/c            ₹6,000

Why are there two entries? Because two things happened:

First: The business earned sales revenue of ₹9,000. ; Second: Inventory costing ₹6,000 left the business.

💡 Aishira Explains the Two Entries

This is one of the most important things to understand. When a business sells goods, there are actually two sides to the transaction. Revenue Side, The business receives or becomes entitled to receive money.

Selling Price = ₹9,000

Cost Side 

The goods sold originally cost the business: ₹6,000

Therefore: Gross Profit = ₹9,000 − ₹6,000 =  ₹3,000

So: Sales tells us how much the customer paid. ; COGS tells us what those goods cost the business.

Periodic vs Perpetual Inventory System

Now let's compare the two systems.

Basis	Periodic System	Perpetual System
Inventory updates	At intervals	Continuously
Physical stock count	Important for determining closing inventory	Used for verification and adjustments
Inventory balance	Not continuously updated	Continuously updated
COGS	Generally determined at period end	Recorded continuously with sales
Technology requirement	Generally simpler	Often benefits from inventory software
Suitability	Smaller/simple operations may use it	Businesses with large or fast-moving inventories often benefit from it

Periodic System — Easy Way to Remember

Think: "I'll check my inventory later." The business records purchases and sales, then determines the actual inventory at the end of the period. Key Word: Periodic = At Intervals

Perpetual System — Easy Way to Remember

Think: "I'll update my inventory whenever something changes." The inventory record is updated as purchases and sales happen.

Key Word: Perpetual = Continuous

Main Difference in One Line

If you remember only one thing from this entire section, remember:

Periodic = Inventory is determined periodically.

Perpetual = Inventory is updated continuously.

Advantages of the Periodic Inventory System

The periodic system can have some practical advantages.

1. Simpler for Small Businesses

A small business with relatively few transactions may find periodic counting easier to manage.

2. Lower System Complexity

It may not require sophisticated inventory software.

3. Useful Where Inventory Movement is Limited

Businesses with simple inventory operations may find periodic stock counting sufficient for their needs.

Disadvantages of the Periodic Inventory System

However, there are also limitations.

1. Less Up-to-Date Information

The business may not know its exact inventory position at every moment.

2. Stock Shortages May Be Discovered Late

If physical counting is done only periodically, missing or damaged stock may remain unnoticed for some time.

3. More Dependence on Physical Counting

Accurate stock counts become especially important.

Advantages of the Perpetual Inventory System

1. Real-Time or Near Real-Time Information

Businesses can have a continuously updated record of inventory.

2. Better Stock Control

Management can identify low-stock items more quickly.

3. Easier Monitoring

Technology can help businesses track individual products, quantities, and movements.

4. Better Decision-Making

Up-to-date inventory information can help management make purchasing and sales decisions.

Disadvantages of the Perpetual Inventory System

1. Higher Setup Cost

Businesses may need inventory software, scanners, systems, and other technology.

2. More Detailed Record-Keeping

Every inventory movement needs to be recorded accurately.

3. System Errors Can Affect Records

If transactions are entered incorrectly or systems are not maintained properly, inventory records may become inaccurate.

Physical Stock Count Under Both Systems

An important point: Even businesses using a perpetual system may physically count inventory. Why? Because accounting records can sometimes differ from actual physical stock.

For example: Recorded inventory: 500 units ; Physical inventory: 490 units ; Difference: 10 units

The business needs to investigate the reason for the difference. Possible reasons include:

• Damage

• Theft

• Wastage

• Recording errors

• Counting mistakes

• Unrecorded transactions

Therefore, physical stock counts can be useful even when a business uses a perpetual system.

A Simple Comparison Example

Suppose a business starts with: 100 units. It purchases: 50 units. 

Then sells: 30 units. 

Under a Perpetual System : The inventory record can be updated continuously: 100 + 50 = 150. Then: 150 − 30 = 120 units. The system can show: Inventory = 120 units

Under a Periodic System = The business may record the purchases and sales separately and determine the actual inventory through a physical count at the end of the period.

If the physical count shows: 120 units, then closing inventory is determined as 120 units.

🧠 Memory Trick

Use this simple comparison: P = Periodic = Pause and Count. 

Inventory is checked at intervals. P = Perpetual = Persistent Updates. 

Inventory keeps getting updated. Both begin with P, so remember the second word: Periodic = Period ; Perpetual = Permanent/Continuous tracking

Common Mistakes

Mistake 1: Thinking Perpetual Means No Physical Counting

Not necessarily. Businesses can still perform physical counts to verify their records.

Mistake 2: Thinking Periodic Means Inventory is Never Recorded

Inventory-related transactions are still recorded. The key difference is that the inventory balance isn't continuously updated in the same way as under the perpetual system.

Mistake 3: Forgetting the Second Entry in a Perpetual Sale

Under the perpetual system, a sale generally involves:

1. Recording the sales revenue.

2. Recording COGS and reducing inventory.

This is a very important accounting distinction.

Mistake 4: Confusing Sales with COGS

They are not the same. Sales = Selling Price ; COGS = Cost of Goods Sold.  The difference contributes to gross profit.

Quick Revision Table

Concept	Meaning
Periodic Inventory	Inventory determined at intervals
Perpetual Inventory	Inventory updated continuously
Physical Count	Actual counting of inventory
Sales	Revenue from selling goods
COGS	Cost associated with goods sold
Inventory	Goods/materials held by business
Closing Inventory	Inventory remaining at period end

What is Damaged Inventory?

Damaged inventory refers to goods that have been physically damaged and may no longer be in their original condition.

Simple Definition

Damaged inventory is stock that has suffered physical damage and may have reduced value or may no longer be suitable for normal sale.

Damage can happen because of:

• Accidents

• Improper storage

• Water

• Fire

• Mishandling

• Transportation problems

• Natural deterioration

💡 Aishira Explains

Suppose a shop has 100 glass bottles. During transportation, 10 bottles break. The business may still have: 100 bottles in its records but physically, only: 90 usable bottles remain. The damaged bottles need to be identified and appropriately dealt with in the accounting and inventory records.

🌍 Example of Damaged Inventory

Suppose a clothing store has a stock of 500 shirts. During storage, 20 shirts are damaged by water.

The damaged shirts may:

• Be completely unsellable.

• Be sold at a discount.

• Require repair before being sold.

Their treatment depends on their condition and the amount that can realistically be recovered from them. The important point is: Damaged inventory may no longer have the same value as normal inventory.

What is Obsolete Inventory?

Obsolete inventory is inventory that has become outdated or no longer has normal demand or usefulness.

Simple Definition

Obsolete inventory is stock that has become outdated or has lost its normal market demand or usefulness.

This is particularly common in industries where products change quickly.

For example:

• Technology

• Electronics

• Fashion

• Mobile devices

• Computer components

💡 Aishira Explains

Imagine an electronics store has an older model of a device. A newer model is launched with better features. Customers now prefer the newer model. The older stock may still physically exist, but its ability to generate the original expected selling price may have fallen. That stock can become obsolete or outdated inventory.

🌍 Example of Obsolete Inventory

Suppose a computer store purchased 100 units of an older processor model. A newer generation is launched. Customers now prefer the newer version. The old processors may become difficult to sell at their original price. The business may therefore need to reconsider the value of that inventory.

What is Slow-Moving Inventory?

Slow-moving inventory refers to stock that is sold or consumed much more slowly than expected.

Simple Definition

Slow-moving inventory is stock that remains unsold or unused for a relatively long period because demand or usage is low.

Slow-moving does not necessarily mean the inventory is worthless. It simply means that it is taking longer than expected to move through the business.

🌍 Example

Suppose a clothing store normally sells a particular jacket quickly. But one particular design has remained in the store for six months. The jacket is still in good condition. However, customer demand is low. This is an example of slow-moving inventory.

Slow-Moving vs Obsolete Inventory

These two concepts are related but not identical.

Slow-Moving Inventory	Obsolete Inventory
Still has some demand or usefulness	May have little or no normal demand
Takes longer to sell	May be outdated
May still be sold normally or with a discount	May need significant reduction in value
Not necessarily worthless	May have very limited recoverable value

🧠 Memory Trick

Remember: Slow-moving = Difficult to sell quickly ; Obsolete = Outdated or no longer normally useful

What is Unsellable Inventory?

Some inventory may become unsellable.

Simple Definition

Unsellable inventory is stock that cannot reasonably be sold to customers in its current condition.

Examples may include:

• Completely damaged products.

• Expired products.

• Severely defective goods.

• Products that no longer meet required standards.

Such inventory needs appropriate accounting treatment.

What Happens When Inventory Loses Value?

This is where inventory valuation becomes important again. Earlier, we learned that inventory has to be valued for accounting purposes. But what if the inventory's expected selling value falls?

For example: A business purchased a product for: ₹1,000

Later, because of damage or falling demand, it can only reasonably recover: ₹700

The business cannot simply ignore the reduction in value. It needs to consider the appropriate accounting treatment based on the applicable accounting standards and circumstances.

Net Realisable Value (NRV)

One important concept connected with inventory valuation is Net Realisable Value, commonly called NRV.

Simple Definition

Net Realisable Value is the estimated selling price of inventory in the ordinary course of business less the estimated costs necessary to complete and sell it.

In simple form: NRV = Estimated Selling Price − Estimated Costs to Complete and Sell

🌍 NRV Example

Suppose a business expects to sell a product for: ₹10,000

But it needs to spend: ₹1,000 to complete and sell the product.

Then: NRV = ₹10,000 − ₹1,000 = ₹9,000

So the estimated net amount that the business expects to realise is ₹9,000.

Why is NRV Important?

NRV helps businesses assess whether the carrying amount of inventory can still be recovered through sale.  This is particularly important when inventory is:

• Damaged.

• Obsolete.

• Slow-moving.

• Outdated.

• Subject to falling selling prices.

The business needs to consider whether the inventory's recorded amount remains appropriate.

Lower of Cost and Net Realisable Value

A fundamental inventory valuation principle under commonly applied accounting standards is that inventory is generally measured at: Lower of Cost and Net Realisable Value (NRV). This means the business compares: Cost with NRV and uses the lower amount, subject to the applicable accounting framework.

🌍 Example

Suppose: Cost of Inventory = ₹50,000 ;  NRV = ₹45,000

Compare:

• Cost = ₹50,000

• NRV = ₹45,000

The lower amount is: ₹45,000

Therefore, the inventory would generally be measured at ₹45,000 under the lower-of-cost-and-NRV principle.

Another Example

Suppose:

Cost = ₹30,000

NRV = ₹35,000

The lower amount is:  ₹30,000

Therefore, inventory would generally remain measured at ₹30,000 under this principle.

🧠 Easy Memory Trick

Remember: Inventory → Compare Cost and NRV → Take the Lower Amount

Why Isn't Inventory Always Valued at Cost?

Because the value that a business can recover from inventory may change. Suppose a business purchased goods for ₹1,00,000.

Later:

• Demand falls.

• Selling prices decline.

• Goods become damaged.

• Products become outdated.

The business may no longer be able to recover the full ₹1,00,000 through sale. Accounting therefore considers the amount that can reasonably be recovered. This helps prevent inventory from being presented at an amount that cannot realistically be recovered.

Inventory Write-Down

When the value of inventory falls below its recorded cost under the applicable accounting rules, the inventory may need to be written down.

Simple Definition

A write-down is a reduction in the recorded value of an asset when its recoverable value has fallen below its carrying amount, where required by the applicable accounting framework.

🌍 Example

Suppose: Inventory Cost = ₹20,000 ; NRV = ₹16,000

Difference: ₹20,000 − ₹16,000 = ₹4,000

The inventory has experienced a potential reduction in value of: ₹4,000

The appropriate accounting treatment would reflect the required write-down under the applicable accounting standards.

What Causes Inventory to Lose Value?

Inventory can lose value for many reasons.

1. Damage

Physical damage may reduce the selling price or make the goods unsellable.

2. Expiry

Products with a limited shelf life may expire before they are sold.

3. Obsolescence

New technology or changing customer preferences can make older products less attractive.

4. Falling Market Prices

If the market selling price falls significantly, inventory may no longer be worth its original cost.

5. Changes in Fashion

Fashion products can quickly become outdated.

6. Changes in Customer Demand

A product that was popular last year may have little demand today.

How Can Businesses Reduce Inventory Losses?

Businesses can take several steps to reduce the risk of inventory becoming damaged or obsolete.

1. Monitor Stock Regularly

Regular inventory checks help businesses identify problems early.

2. Use Proper Storage

Appropriate storage can reduce physical damage.

3. Track Expiry Dates

Businesses dealing with perishable products should monitor expiration dates carefully.

4. Identify Slow-Moving Items

Slow-moving products can be identified before they become obsolete.

5. Improve Purchasing Decisions

Businesses should avoid purchasing excessive quantities without considering expected demand.

6. Use Discounts Where Appropriate

Businesses may sometimes offer discounts to move older inventory before it becomes obsolete.

What is Inventory Loss?

Inventory loss occurs when the business suffers a reduction in inventory quantity or value.

This may happen because of:

• Theft

• Damage

• Wastage

• Expiry

• Obsolescence

• Natural deterioration

• Errors

The accounting treatment depends on the reason for the loss and the applicable accounting rules.

Inventory Shrinkage

A related concept is inventory shrinkage.

Simple Definition

Inventory shrinkage is the difference between the inventory recorded in the books and the inventory actually available according to a physical count.

🌍 Example

Accounting records show: 1,000 units

Physical count shows: 980 units

Difference: 20 units

Those missing 20 units represent inventory shrinkage, subject to investigation and appropriate accounting treatment.

Possible causes include:

• Theft

• Damage

• Wastage

• Recording errors

• Counting mistakes

Damaged vs Obsolete vs Slow-Moving

Let's quickly compare them.

Type	Main Problem	Example
Damaged	Physical condition has deteriorated	Broken glassware
Obsolete	Outdated or no longer normally useful	Old technology
Slow-moving	Takes a long time to sell	Unpopular clothing
Unsellable	Cannot reasonably be sold	Expired product

A single product can sometimes fall into more than one category. For example, an old electronic device could be both obsolete and slow-moving.

Common Mistakes

Mistake 1: Thinking Damaged Inventory Has No Value

Not every damaged item is worthless. Some damaged goods may still be sold at a discount or after repair. The amount recoverable needs to be considered.

Mistake 2: Thinking Slow-Moving Means Obsolete

Slow-moving inventory may still have demand. Obsolete inventory is generally outdated or no longer normally useful or marketable.

Mistake 3: Ignoring NRV

Inventory valuation isn't only about what the business originally paid. The business also needs to consider what it can reasonably recover from the inventory.

Mistake 4: Thinking Inventory Always Remains at Original Cost

Inventory may require a reduction in value when its recoverable amount falls below its carrying amount, as required by the applicable accounting framework.

🧠 Memory Trick

For inventory valuation, remember: COST vs NRV → LOWER

And for inventory problems: DAMAGED → OBSOLETE → SLOW → UNSOLD

These are warning signs that inventory may need closer attention.

Important Inventory Formulas

Here are the most useful formulas you should remember.

1. Cost of Goods Sold (COGS)

The basic formula is: COGS = Opening Inventory + Net Purchases − Closing Inventory

Where: Net Purchases = Purchases + Direct Purchase Expenses − Purchase Returns

Depending on the accounting context, freight or other directly attributable purchase costs may be included in the cost of inventory.

2. Gross Profit

Once you know COGS, you can calculate Gross Profit. Gross Profit = Sales − COGS

🌍 Example

Suppose:

• Sales = ₹1,50,000

• COGS = ₹90,000

Therefore: Gross Profit = ₹1,50,000 − ₹90,000 = ₹60,000

So the business has earned a gross profit of ₹60,000.

3. Gross Loss

If COGS is greater than sales, the business has a gross loss. Gross Loss = COGS − Sales

🌍 Example

Suppose:

• Sales = ₹70,000

• COGS = ₹85,000

Then: Gross Loss = ₹85,000 − ₹70,000 = ₹15,000

4. Average Inventory

Average inventory is commonly calculated as: Average Inventory = (Opening Inventory + Closing Inventory) ÷ 2

🌍 Example

Suppose:

• Opening Inventory = ₹40,000

• Closing Inventory = ₹60,000

Then: Average Inventory = (₹40,000 + ₹60,000) ÷ 2 = ₹50,000

5. Inventory Turnover Ratio

A commonly used formula is: Inventory Turnover Ratio = COGS ÷ Average Inventory

🌍 Example

Suppose:

• COGS = ₹4,00,000

• Average Inventory = ₹50,000

Then: Inventory Turnover Ratio = ₹4,00,000 ÷ ₹50,000 = 8 times

This means the inventory was turned over approximately 8 times during the period.

6. Net Realisable Value (NRV)

The basic formula is: NRV = Estimated Selling Price − Estimated Costs to Complete and Sell

🌍 Example

Suppose:

• Estimated Selling Price = ₹20,000

• Estimated Costs to Complete and Sell = ₹2,000

Then:  NRV = ₹20,000 − ₹2,000  = ₹18,000

7. Weighted Average Cost

Under the weighted average method: Weighted Average Cost per Unit = Total Cost of Inventory Available ÷ Total Units Available

🌍 Example

Suppose a business purchases:

• 100 units at ₹10 = ₹1,000

• 200 units at ₹15 = ₹3,000

Total:

Quantity = 300 units

Total Cost = ₹4,000

Therefore: 

Weighted Average Cost = ₹4,000 ÷ 300 = ₹13.33 per unit approximately

Let's Solve a Complete Inventory Problem

Now let's combine several concepts. Suppose a business has:

• Opening Inventory = ₹30,000

• Purchases = ₹1,00,000

• Purchase Returns = ₹5,000

• Closing Inventory = ₹25,000

• Sales = ₹1,50,000

Step 1: Calculate Net Purchases

Net Purchases = Purchases − Purchase Returns

= ₹1,00,000 − ₹5,000 = ₹95,000

Step 2: Calculate COGS

COGS = Opening Inventory + Net Purchases − Closing Inventory

= ₹30,000 + ₹95,000 − ₹25,000 = ₹1,00,000

Therefore: COGS = ₹1,00,000

Step 3: Calculate Gross Profit

Gross Profit = Sales − COGS

= ₹1,50,000 − ₹1,00,000 = ₹50,000

Therefore: Gross Profit = ₹50,000

Another Simple Example

Suppose:

• Opening Inventory = ₹50,000

• Purchases = ₹2,00,000

• Closing Inventory = ₹70,000

• Sales = ₹3,00,000

COGS: ₹50,000 + ₹2,00,000 − ₹70,000 = ₹1,80,000

Gross Profit: ₹3,00,000 − ₹1,80,000 = ₹1,20,000

So: COGS = ₹1,80,000 ; Gross Profit = ₹1,20,000

Inventory Revision: The Complete Picture

What is Inventory?

Inventory is the stock of goods, materials, or products that a business holds for:

• Sale

• Production

• Consumption

• Use in business operations

Main Types of Inventory

Raw Materials = Materials used to manufacture products.

Work-in-Progress = Goods that are still being manufactured.

Finished Goods = Completed products ready for sale.

MRO Supplies = Materials used to support business operations, maintenance, and repairs.

Inventory Valuation

Inventory needs to be assigned a monetary value. Common approaches discussed include:

• FIFO

• Weighted Average Cost

Inventory is generally measured at the lower of cost and NRV, subject to the applicable accounting framework.

Inventory Management

Inventory management focuses on maintaining appropriate stock levels.

The business tries to avoid: Too much stock → Overstocking and Too little stock → Understocking

It also monitors:

• Reorder levels

• Safety stock

• Stock turnover

• Slow-moving inventory

Inventory Accounting

Inventory-related transactions include:

• Purchases

• Sales

• Purchase Returns

• Sales Returns

• Closing Inventory

• Inventory adjustments

Basic journal entries include:

Purchase

Purchases A/c       Dr.
      To Cash/Supplier A/c

Cash Sale

Cash A/c            Dr.
      To Sales A/c

Purchase Return

Supplier A/c        Dr.
      To Purchase Returns A/c

Sales Return

Sales Returns A/c   Dr.
      To Customer A/c

Under a perpetual inventory system, the cost of goods sold is also recorded when goods are sold.

Periodic vs Perpetual

Periodic System = Inventory is determined at intervals, usually using physical stock counts.

Perpetual System = Inventory records are updated continuously as inventory transactions occur.

Easy Memory Trick

Periodic = Periodically check

Perpetual = Continuously update

Damaged and Obsolete Inventory

Inventory can lose value because of:

• Damage

• Expiry

• Obsolescence

• Falling demand

• Falling selling prices

Businesses need to assess whether the recorded value of inventory remains appropriate.

Inventory Shrinkage

Inventory shrinkage occurs when: Recorded Inventory ≠ Actual Physical Inventory

For example:

Books show: 1,000 units

Physical count shows: 980 units

Difference: 20 units

The business should investigate the difference and make any required accounting adjustment.

Frequently Asked Questions (FAQs)

1. What is inventory in accounting?

Inventory is the stock of goods, materials, or products held by a business for sale, production, consumption, or use in business operations.

2. What is the difference between stock and inventory?

In many business and accounting contexts, stock and inventory are used interchangeably to refer to goods and materials held by a business. However, the exact meaning can vary depending on the context. 

3. What are the main types of inventory?

The major types include:

• Raw Materials

• Work-in-Progress

• Finished Goods

• MRO Supplies

4. What is closing inventory?

Closing inventory is the stock remaining with a business at the end of an accounting period.

5. What is opening inventory?

Opening inventory is the inventory available at the beginning of an accounting period. For a business continuing from one accounting period to the next, the previous period's closing inventory generally becomes the next period's opening inventory.

6. What is COGS?

COGS stands for Cost of Goods Sold. It represents the cost associated with goods sold during an accounting period. A basic formula is: COGS = Opening Inventory + Net Purchases − Closing Inventory

7. Why is closing inventory deducted from COGS?

Because closing inventory represents goods that remain unsold at the end of the period. Those goods have not yet been treated as goods sold for the current period. Therefore, closing inventory is deducted when calculating COGS.

8. What is FIFO?

FIFO stands for First-In, First-Out. Under FIFO, the earliest purchased inventory is assumed to be sold or issued first.

9. What is the Weighted Average Method?

The weighted average method calculates an average cost per unit using the total cost and total quantity of inventory available.

10. What is inventory turnover ratio?

Inventory turnover ratio measures how quickly inventory is sold or used and replaced during a period.
A commonly used formula is: Inventory Turnover Ratio = COGS ÷ Average Inventory

11. What is NRV?

NRV stands for Net Realisable Value. It is the estimated selling price of inventory less the estimated costs necessary to complete and sell it.

12. What is damaged inventory?

Damaged inventory is stock that has suffered physical damage and may have reduced value or may no longer be suitable for normal sale. 

13. What is obsolete inventory?

Obsolete inventory is stock that has become outdated or has lost its normal usefulness or demand.

14. What is slow-moving inventory?

Slow-moving inventory is stock that takes a relatively long time to sell or use because of low or slow demand.

15. What is overstocking?

Overstocking means holding more inventory than is reasonably required. It can tie up cash and increase storage, damage, expiry, and obsolescence risks.

16. What is understocking?

Understocking means having insufficient inventory to meet normal business requirements. It can result in stockouts, lost sales, or production delays.

17. What is safety stock?

Safety stock is additional inventory kept as a buffer against unexpected increases in demand or delays in supply.

18. What is reorder level?

Reorder level is the inventory level at which a business should place a new order to replenish stock before it runs out, based on its demand and replenishment time.

19. What is the difference between periodic and perpetual inventory systems?

Under the periodic system, inventory is determined at regular intervals. Under the perpetual system, inventory records are continuously updated as inventory transactions occur.

20. Why is inventory important for a business?

Inventory is important because it helps businesses:

• Meet customer demand.

• Continue production.

• Generate sales.

• Maintain smooth operations.

At the same time, excessive inventory can tie up cash and increase storage and other costs.

🧠 Final Memory Map

If you want to remember the entire topic quickly, use this sequence:

INVENTORY → TYPES → VALUATION → MANAGEMENT → ACCOUNTING → SYSTEMS → LOSSES → FORMULAS

INVENTORY

What goods and materials does the business hold?

↓

TYPES

Raw Materials → WIP → Finished Goods → MRO

↓

VALUATION

How much is the inventory worth?

↓

MANAGEMENT

How much stock should the business maintain?

↓

ACCOUNTING

How are purchases, sales, and returns recorded?

↓

SYSTEMS

Periodic vs Perpetual

↓

LOSSES

Damage → Obsolescence → Slow Movement → Shrinkage

↓

FORMULAS

COGS → Gross Profit → Average Inventory → Turnover → NRV. That's the complete picture.

What's Next?

What is a Bank Reconciliation Statement (BRS)? Meaning, Objectives & Complete Beginner's Guide (2026)