COGS in Accounting (Cost Guide)

Cost of goods sold (COGS) is the cost of inventory a business sold during a reporting period. A common formula is beginning inventory plus net purchases and eligible inventory costs, minus ending inventory. COGS is an expense on the income statement, not the same as cash paid for goods. The method used to assign costs affects reported COGS and profit.

When you compare prices, plan a budget, or read a company’s financial statements, accounting terms can make simple questions feel complicated. COGS is one of those terms: understanding it helps you see how a business moves from buying or making products to reporting profit.

Accurate inventory costs can also help a business spot waste, including materials that are damaged or left unused. COGS is not an environmental score, though. A cost belongs in inventory only when accounting rules support including it.

COGS Overview: Definition, Accounting Framework, and Business Context

COGS measures the cost assigned to products sold in a period. It applies to both businesses that buy finished goods to resell and manufacturers that make goods. The applicable accounting framework, such as U.S. GAAP or IFRS, guides how inventory costs are measured and reported.

Inventory is an asset: goods a business holds for sale or uses to make goods for sale. A store may hold finished items bought from suppliers. A manufacturer may hold raw materials, partly finished products, and completed goods.

COGS appears on the income statement. It is deducted from net sales to calculate gross profit:

Gross profit = net sales − COGS

Net sales means sales after deductions such as sales returns and allowances. Gross profit is not the same as net income, because it does not yet subtract other expenses, such as office costs or interest.

The two main business types handle inventory differently:

• Merchandising business: Buys finished products and resells them. Its inventory cost can include the purchase price and eligible costs to get the goods to their location and condition for sale.
• Manufacturer: Makes products. Inventory cost can include raw materials, direct labor, and production overhead, such as factory costs tied to making goods.

Both U.S. GAAP and IFRS generally require inventory costs to include costs of purchase and production needed to bring inventory to its present location and condition. Selling costs and general administrative costs not tied to production are generally period expenses, not inventory costs.

The measurement rules differ in some cases. Under U.S. GAAP, inventory is generally measured at the lower of cost and net realizable value (NRV), which is the expected selling price less the costs to complete and sell it. Eligible inventory measured using LIFO or the retail method follows a lower-of-cost-or-market rule instead. Under IFRS, inventory is measured at the lower of cost and NRV. IFRS does not permit LIFO.

COGS Calculation: Inventory Costs, Formulas, and Cost-Flow Methods

The COGS formula connects the inventory available for sale with the inventory left at period-end. To calculate it, identify eligible costs, account for returns and other adjustments, and use the cost-flow assumption the business applies to comparable inventory.

For a merchandising business, a practical version of the formula is:

Beginning inventory + net purchases and other eligible inventory costs − ending inventory = COGS

Net purchases usually reflect purchases after purchase returns, allowances, and discounts. Freight-in or other delivery costs may be included when they are needed to bring purchased goods to the right location and condition. The exact treatment depends on the facts and accounting rules.

A manufacturer uses the same basic inventory equation, but production costs must first be assigned to inventory. These can include direct materials, direct labor, and production overhead. Costs unrelated to making the product, such as general office expenses or selling costs, are usually expensed in the period.

Cost-flow assumptions determine which eligible costs are assigned to COGS and which remain in ending inventory. They do not have to match the physical order in which goods leave a warehouse. A business should apply its method consistently to comparable inventory.

Here is a small example. A business begins with 10 units costing $10 each, buys 10 more at $12 each, and sells 12. It has 8 units left. The table shows how different methods assign the $220 total cost:

Under FIFO, the oldest costs are assigned to COGS first. Under weighted average, the average cost is $11 per unit ($220 ÷ 20). Under LIFO, the newest costs are assigned to COGS first. In this rising-cost example, FIFO gives lower COGS than LIFO. That result is not guaranteed when costs move differently.

Worked example: I use this simple case to show the calculation, not to describe a real company. If beginning inventory is $5,000, net purchases and eligible costs are $18,000, and ending inventory is $4,000, then COGS is $19,000. The arithmetic is $5,000 + $18,000 − $4,000. The business’s chosen cost-flow assumption and correct inventory records must support those figures.

Recording, Reconciliation, and Common Accounting Errors

Recording COGS means recognizing the cost of sold inventory as an expense and reducing the inventory asset. Businesses may use a perpetual system, which updates inventory records as transactions occur, or a periodic system, which calculates COGS at the end of a period.

In a perpetual system, a sale usually has two entries. The first records the sale and related receivable or cash. The second records the cost:

• Debit COGS
• Credit Inventory

When goods are bought, the business records the cost in Inventory, rather than treating the purchase as COGS immediately. A periodic system records purchases during the period, then uses beginning inventory, net purchases, and a physical count of ending inventory to calculate COGS.

To check the result at period-end:

• Compare inventory records with a physical count.
• Investigate missing, damaged, or wrongly recorded items.
• Check purchase returns, allowances, and eligible delivery costs.
• Confirm which goods the business owns at the cutoff date.
• Recalculate ending inventory using the chosen cost method.

Cutoff matters because goods in transit may belong to the buyer or seller depending on the purchase terms. A count error can distort both COGS and gross profit. If ending inventory is too high, COGS is too low and gross profit is too high. If ending inventory is too low, the opposite happens. A beginning-inventory error can also affect COGS.

If an ending-inventory error is not corrected, its effect generally reverses in the next period through beginning inventory. That can make year-to-year trends misleading. A business should investigate the cause and correct errors under the accounting rules that apply.

COGS is also not cash paid for inventory. A business may buy goods on credit, pay later, or hold goods for a time before selling them. The purchase first becomes inventory; its cost becomes COGS when assigned to goods sold. Keep this distinction in mind when comparing an income statement with cash flows.

Using COGS to Assess Gross Margin and Business Performance

COGS helps explain how much of each sales dollar remains after accounting for the cost of goods sold. It is most useful when read with net sales, gross profit, and gross margin, and when comparisons use consistent methods and periods.

Calculate gross margin as:

Gross margin = gross profit ÷ net sales

If net sales are $30,000 and COGS is $19,000, gross profit is $11,000. Gross margin is about 36.7% ($11,000 ÷ $30,000). This means gross profit is about 36.7 cents per dollar of net sales, before other expenses.

A change in COGS can have several causes: changes in supplier prices, production costs, sales volume, waste, product mix, or inventory valuation. A change in gross margin does not, by itself, reveal which cause is responsible. Check the underlying records before drawing conclusions.

Cost-flow methods can also affect reported profit when unit costs change. In the rising-cost example, FIFO produces lower COGS and higher ending inventory than LIFO. That affects reported gross profit, but does not by itself show which business is more efficient. When comparing companies, check their accounting policies and the periods being compared.

A practical review can follow this sequence:

• Confirm net sales and the reporting period.
• Confirm the inventory method and accounting framework.
• Recheck beginning inventory, purchases, eligible costs, and ending inventory.
• Compare gross margin with prior periods, while noting price and product changes.
• Investigate unusual movements rather than assuming COGS alone explains them.

Key takeaway: COGS is a measure of the cost assigned to goods sold, not a standalone measure of cash use, waste, or business success. Reliable interpretation starts with sound inventory records and a clear view of the cost method.

COGS FAQs

These quick answers address common questions about calculating and interpreting cost of goods sold. The right answer can depend on the business, the inventory system, and the accounting framework, so use the same rules consistently and check the details behind each figure.

What is the basic COGS formula?

Beginning inventory plus net purchases and other eligible inventory costs, minus ending inventory, equals COGS. For manufacturers, eligible production costs are included in the inventory calculation.

Is COGS an expense or an asset?

COGS is an expense on the income statement. Before goods are sold, their eligible costs are generally held as inventory, an asset.

Are purchases the same as COGS?

No. A purchase normally enters inventory first. Its cost becomes COGS when the related goods are sold and their cost is assigned to the sale.

Does COGS equal cash paid for inventory?

No. A business may buy inventory on credit or pay before selling it. COGS reflects the cost assigned to goods sold, not the timing of payment.

Which costs can be included in COGS?

COGS includes the cost assigned to sold goods. Inventory cost can include purchase or production costs needed to bring goods to their present location and condition. Selling and unrelated general administrative costs are generally excluded from inventory.

Can a business use LIFO under IFRS?

No. IFRS does not permit LIFO. U.S. GAAP permits LIFO, while both frameworks allow FIFO and weighted average, subject to their rules.

How does ending inventory affect COGS?

Ending inventory is subtracted in the COGS formula. If it is overstated, COGS is understated and gross profit is overstated for that period.

What is the difference between gross profit and gross margin?

Gross profit is net sales minus COGS. Gross margin is gross profit divided by net sales, usually shown as a percentage.

Why might two similar companies report different COGS?

They may use different permitted cost-flow assumptions, face different purchase or production costs, or hold different product mixes. Check accounting methods and business details before comparing results.

(This article was written by one of our staff writers, Alan Westbrook. Visit our Meet the Team page.)