Cost of Goods Sold (COGS) is the direct cost of producing or acquiring the goods a business actually sold during a period. It appears on the income statement directly below revenue, and subtracting it gives gross profit, the first and most fundamental measure of whether a business's core sales activity is profitable before any overhead is considered.
FORMULA
Cost of Goods Sold = Beginning Inventory + Purchases − Ending Inventory
EXAMPLE
A distributor starts the quarter with $380,000 in inventory, purchases $1,200,000 more during the period, and ends with $420,000 in inventory.
COGS = $380,000 + $1,200,000 − $420,000 = $1,160,000.
This is the cost of what was actually sold, distinct from what was purchased during the period.
Notice that purchases and COGS are not the same figure. A business can buy more inventory than it sells in a given period, which increases ending inventory and keeps that spending off COGS until the goods actually sell in a later period.
What is excluded is just as important: selling expenses, administrative salaries, marketing, and freight-out to customers are operating expenses, not COGS, even though they are real costs of running the business. Miscoding these into COGS distorts gross margin and makes it harder to compare performance period to period.
These terms are frequently used interchangeably, and in most contexts they mean the same thing. Where a distinction is drawn, cost of goods sold is sometimes used specifically for businesses that sell physical products, while cost of sales is used more broadly to include service-based costs as well, such as the direct labor cost of delivering a service. In practice, most financial statements use one term or the other consistently rather than distinguishing between them.
EXAMPLE
At the point of sale (perpetual inventory system)
Debit: Cost of Goods Sold $1,160,000
Credit: Inventory $1,160,000
Inventory decreases as goods leave, and the cost moves to the income statement in the same period as the related revenue.
Under a periodic inventory system, COGS is not recorded transaction by transaction. Instead, it is calculated once at period end using the formula above, based on a physical inventory count, and posted as a single adjusting entry. Most modern accounting systems use the perpetual method, updating COGS with each sale, because it gives real-time inventory visibility rather than only a period-end snapshot.
COGS is only as accurate as the inventory and purchase data feeding it. If supplier invoices for inventory purchases are sitting unprocessed rather than posted, the purchases figure in the formula is understated, which distorts both COGS and the resulting gross margin for the period, even though the underlying inventory may already be sitting in the warehouse.
This is the same accuracy dependency that runs through the balance sheet and the AP aging report: the formula itself is simple, but every input depends on invoice processing having kept pace with what has actually been received.
