perpetual inventory method (PIM)

System of inventory control in which the number of units of any inventory item (and the total value of inventory) on any day can be obtained from the stock records. In this method (1) all additions (purchases) and withdrawals (sales or consumption) are recorded in inventory cards as they occur to provide a running balance of quantity and cost of items, (2) a certain number of items are counted every day (or week or month) so that, by the year end, every item has been actually (physically) counted at least once. If there is any mismatch (due to human error, leakage, pilferage, loss) between the physical quantity and the quantity shown in inventory cards, the records are adjusted accordingly. Also called continuous inventory method. See also periodic inventory method.