Periodic inventory is a system of inventory in which updates are made on a periodic basis. This differs from perpetual inventory systems, where updates are made as seen fit.

In a periodic inventory system no effort is made to keep up-to-date records of either the inventory or the cost of goods sold. Instead, these amounts are determined only periodically - usually at the end of each year. This physical count determines the amount of inventory appearing in the balance sheet. The cost of goods sold for the entire year then is determined by a short computation.

• Robert F. Malik, Jan R. Williams, Susan F. Haka & Mark S. Bettner. Financial accounting, eleventh edition, McGraw-Hill.