The sales revenues minus the cost of goods sold is gross profit.
Cost of goods sold is calculated in one of two ways. One way is to adjust the cost of the goods purchased or manufactured by the change in inventory of finished goods. For example, if 1,000 units were purchased or manufactured but inventory increased by 100 units then the cost of 900 units will be the cost of goods sold. If 1,000 units were purchased but the inventory decreased by 100 units then the cost of 1,100 units will be the cost of goods sold.
The second way to calculate the cost of goods sold is to use the following costs: beginning inventory + the cost of goods purchased or manufactured = cost of goods available – ending inventory.
When costs change during the accounting period, a cost flow will have to be assumed. Cost flow assumptions include FIFO, LIFO, and average.