Definition of Average total cost

In economics, average cost is equal to total cost divided by the number of goods produced (Quantity-Q). It is also equal to the sum of average variable costs (total variable costs divided by Q) plus average fixed costs (total fixed costs divided by Q). Average costs may be dependent on the time period considered (increasing production may be expensive or impossible in the short term, for example). Average costs affect the supply curve and are a fundamental component of supply and demand.

Under the average-cost method, it is assumed that the cost of inventory is based on the average cost of the goods available for sale during the period. Average cost is computed by dividing the total cost of goods available for sale by the total units available for sale. This gives a weighted-average unit cost that is applied to the units in the ending inventory.