What Is Inventory? Types and Meaning in Accounting

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Inventory is the stock of goods and materials a business holds in order to sell them or to turn them into products it will sell. In accounting, inventory covers raw materials, work-in-progress and finished goods. It is reported as a current asset on the balance sheet because the company expects to convert it into sales, and then cash, within its normal operating cycle. When an item is sold, its cost leaves inventory and becomes an expense called cost of goods sold (COGS) on the income statement.

How Inventory Works in Accounting

A company records inventory at cost when it acquires or produces the goods. Cost generally includes the purchase price plus the costs needed to bring the goods to their current location and condition, such as inbound freight and, for manufacturers, direct labor and allocated production overhead. Selling costs, such as advertising, are not part of inventory cost.

The link between inventory and the income statement follows a basic identity:

COGS = Beginning inventory + Purchases (or production costs) − Ending inventory

A company tracks these flows under one of two systems:

• Perpetual system: every purchase and sale updates the inventory records as it happens, so the book balance is always current.
• Periodic system: purchases are recorded as they occur, but inventory on hand is counted at the end of the period, and COGS is derived from the formula above.

Even under a perpetual system, businesses take physical counts, often annually, to compare records with what is actually on hand. Differences from theft, damage or recording errors are written off.

On the balance sheet, inventory appears among current assets, usually after cash and receivables, because it is a step further from cash.

Types of Inventory

Raw materials

Raw materials are inputs that have not yet entered production. Steel and aluminum held by a carmaker, flour stored by a bakery and crude oil at a refinery are all raw materials. One company’s finished good can be another’s raw material: a chip maker sells finished chips that a device maker records as raw materials.

Work-in-progress

WIP is partially completed product, sometimes called inventory on the production floor. A half-assembled aircraft or a yacht still in the shipyard is WIP. Its carrying value includes the materials already used plus the labor and overhead applied so far.

Finished goods and merchandise

Finished goods have completed production and are ready to sell. Retailers and wholesalers, which buy goods for resale rather than making them, usually call this inventory merchandise. Clothing in a store, cars on a dealer’s lot and electronics in a warehouse are typical examples.

Supplies

Some businesses also carry maintenance, repair and operating (MRO) supplies or packaging. The IRS treats supplies as inventory items when they physically become part of the product, such as packaging or containers. Supplies used to run the business, such as office paper, are generally expensed or recorded as a separate supplies asset rather than as inventory.

Consignment inventory

Under a consignment arrangement, a supplier (the consignor) places goods with a retailer or other customer (the consignee) but keeps ownership. The consignee pays only when it sells the goods to an end customer or uses them in its own production. Because ownership stays with the supplier, the goods remain in the supplier’s inventory, not the retailer’s, even though they sit in the retailer’s store.

How Inventory Is Valued: FIFO, LIFO and Weighted Average

When identical items are bought at different prices, the company needs a cost flow assumption to decide which cost goes to COGS and which stays in inventory. The physical flow of goods does not have to match the method chosen.

• First-in, first-out (FIFO): the earliest costs go to COGS; ending inventory reflects the most recent costs.
• Last-in, first-out (LIFO): the latest costs go to COGS; ending inventory reflects the oldest costs. Permitted under U.S. GAAP but prohibited under IFRS.
• Weighted average: COGS and ending inventory are both valued at the average cost of the units available during the period.

Businesses selling unique, high-value items (such as cars or jewelry) may use specific identification, tracking the actual cost of each unit.

Worked example (hypothetical)

A retailer buys 100 units at $10 in January and 100 units at $12 in February, for $2,200 of goods available. It sells 150 units.

Each method splits the same $2,200 differently. With rising purchase costs, as in this example, LIFO produces the highest COGS and lowest taxable profit, which is why it has been attractive to U.S. companies during periods of inflation. FIFO produces a higher profit and a balance sheet value closer to current replacement cost. If costs fall, these effects reverse. A company using LIFO for taxes in the U.S. must also use it in its financial statements (the LIFO conformity rule).

Does inventory always stay at purchase cost?

No. If inventory loses value through damage, obsolescence or falling prices, it must be written down. Under U.S. GAAP, inventory measured with FIFO or weighted average is carried at the lower of cost and net realizable value (estimated selling price minus costs to complete and sell); LIFO and retail-method inventory use the older lower of cost or market test. IFRS applies lower of cost and net realizable value to all inventory and allows a write-down to be reversed if values recover. U.S. GAAP does not allow that reversal.

Inventory Turnover and Days in Inventory

Inventory turnover measures how often a company sells and replaces its stock over a period:

Inventory turnover = COGS ÷ Average inventory

Average inventory is usually (beginning inventory + ending inventory) ÷ 2. COGS is used rather than revenue because both COGS and inventory are stated at cost.

A related figure converts turnover into time:

Days in inventory = 365 ÷ Inventory turnover

Hypothetical example: a company reports annual COGS of $600,000, beginning inventory of $140,000 and ending inventory of $100,000. Average inventory is $120,000, so turnover is 5.0 times and days in inventory is 365 ÷ 5 = 73 days. On average, goods sit about ten weeks before being sold.

A higher turnover means stock moves faster, which lowers holding costs and frees cash for other uses. A lower turnover can point to overstocking, slowing demand or obsolete goods. Neither reading is good or bad in isolation: a grocer and an aircraft manufacturer will show very different turnover because of what they sell. The ratio is most useful compared with the same company’s history and with direct competitors.

Why Inventory Matters

For manufacturers, distributors and retailers, inventory is often one of the largest current assets, and it directly drives COGS, gross margin and working capital. Building inventory consumes cash before any sale happens, so a company growing its stock faster than its sales will see operating cash flow lag reported earnings.

Inventory management is a balance between two costs:

• Holding too much: storage, insurance, financing, spoilage and obsolescence, plus the opportunity cost of capital tied up in goods.
• Holding too little: stockouts, lost sales, delayed production and customers who switch to competitors.

Just-in-time (JIT) systems aim to receive materials or produce goods only when they are needed, cutting holding costs. JIT depends on reliable suppliers and accurate forecasts; a supply disruption hits a lean operation faster than one carrying buffer stock.

Limitations of Inventory Figures

A reported inventory balance is an accounting estimate, not a market price. Several factors limit what it shows:

• Method choice affects comparability. Two companies with identical goods can report different inventory values and profits if one uses LIFO and the other FIFO. U.S. LIFO users disclose a LIFO reserve (the gap between LIFO and FIFO values), which analysts use to put them on a common basis.
• Old LIFO layers can distort the balance. A company that has used LIFO for many years may carry inventory at costs from decades earlier, well below current value. Selling down those layers can temporarily inflate profit.
• Write-downs depend on judgment. Estimates of selling prices and obsolescence involve management assumptions, and delayed write-downs can overstate assets.
• A single balance is a snapshot. Year-end inventory can differ sharply from mid-year levels for seasonal businesses, so ratios built on one or two balance sheet dates may not represent the whole year.
• Turnover does not explain itself. A falling ratio could reflect weaker demand, deliberate stockpiling ahead of a launch or a price increase from suppliers. The cause has to be found elsewhere in the financial statements and management commentary.

Inventory vs. Related Terms

Inventory vs. COGS. Inventory is the cost of goods still on hand, shown on the balance sheet. COGS is the cost of goods already sold during the period, shown on the income statement. The same dollar moves from the first to the second when a sale occurs.

Inventory vs. fixed assets (capital goods). Machinery, vehicles and buildings that a company uses to operate are long-term assets subject to depreciation, not inventory. The same item can be either, depending on the holder: a truck on a dealer’s lot is inventory, while the truck a bakery uses for deliveries is equipment.

FAQs

The Bottom Line

Inventory shapes gross margin, working capital and cash flow for manufacturers, distributors and retailers, so investors and managers reading their statements should look past the single balance. Valuation method, write-down judgments and seasonal timing all affect the reported figure. Turnover ratios work best when compared with the company's own history and direct competitors, with the cause of any change traced through the rest of the financial statements.