3. Periodic versus Perpetual Inventory System

b. describe different inventory valuation methods (cost formulas);

## c. calculate and compare cost of sales, gross profit, and ending inventory using different inventory valuation methods and using perpetual and periodic inventory systems; ## d. calculate and explain how inflation and deflation of inventory costs affect the financial statements and ratios of companies that use different inventory valuation methods;

What is the perpetual inventory system? The perpetual inventory system updates inventory accounts after each purchase or sale. Inventory quantities are updated continuously. When there is a sale, inventory is reduced and COGS is calculated.

What is the periodic inventory system? The periodic inventory system records inventory purchase or sale in the “Purchases” account. The “Inventory” account is updated on a periodic basis, at the end of each accounting period (e.g., monthly, quarterly). Cost of goods sold or cost of sale is computed from the ending inventory figure.

Is perpetual FIFO the same as periodic FIFO? The end result under perpetual FIFO is the same as under periodic FIFO. In other words, the first costs are the same whether you move the cost out of inventory with each sale (perpetual) or whether you wait until the year is over (periodic).