Perpetual Inventory

Perpetual inventory is an inventory system in which stock records are updated whenever a purchase, receipt, sale, transfer, production issue, waste entry or other inventory transaction is recorded. It gives a business a running estimate of the quantity and value of stock on hand without waiting for the next full physical count.

How perpetual inventory works

Each inventory transaction changes the recorded balance. When a restaurant receives a case of olive oil, the system increases the stock quantity. When a recipe or sales integration records usage, the system reduces it. Transfers between locations and documented waste or adjustments also change the balance.

Examples in restaurant operations

• Receiving: accepted deliveries increase the inventory record.
• Sales and recipes: POS activity may reduce theoretical ingredient usage when menu items are sold.
• Production: ingredients issued to a batch or central kitchen are recorded as consumed or transferred.
• Waste and staff meals: approved entries adjust stock to reflect actual use.
• Transfers: stock moved between storage areas or restaurant locations is recorded at both ends.

Perpetual inventory versus periodic inventory

Perpetual inventory updates records continuously as transactions are entered. Periodic inventory calculates stock and cost at defined intervals, often using physical counts. Many restaurants use a perpetual system but still perform regular physical counts to identify errors, waste, theft or unrecorded transactions.

Why perpetual inventory can be inaccurate

The system’s balance is only as reliable as the transactions entered. Missing receiving entries, incorrect pack sizes, unit conversions, recipe quantities, unrecorded waste and POS mapping errors can create a gap between book inventory and actual stock.

Chef’s tip: reconcile perpetual inventory with regular physical counts. Use variance reports to investigate recurring problems rather than automatically adjusting the system to match the count.