Inventory shrinkage is a shortage between the stock the records say should exist and the quantity or value found through reconciliation. Possible causes include theft, damage, spoilage, missed movements and counting or data-entry errors. The difference is evidence to investigate, not proof of a particular cause.
State whether the measure uses units or value
For a single SKU at a defined count time:
Shortage units = recorded units − physical units
Shortage rate = shortage units / recorded units × 100
If records show 100 units and the count finds 96, the shortage is four units, or 4% of recorded units. If each costs $10, the cost-valued shortage is $40. If physical quantity exceeds recorded quantity, report the overage and investigate it rather than calling it negative theft.
Across unlike products, value shortages at a consistent cost basis. Adding units of flour, gloves and furniture does not create a meaningful portfolio loss measure. A revenue-based shrinkage ratio is another metric entirely:
Revenue-based loss ratio = recognized inventory loss at cost / net revenue × 100
Do not compare a percentage of revenue with a percentage of inventory or food cost as though they use the same denominator.
A worked financial example
Assume an operation records $1,000 of inventory losses in a week and $40,000 of net revenue. The revenue-based loss ratio is 2.5%. If that same weekly loss continued for 52 weeks, the annualized scenario would be $52,000. That is an illustrative run rate, not an industry benchmark.
The $52,000 loss does not mean average inventory rose by $52,000 or that annual carrying cost rose by the same amount. Inventory balance, replacement purchases, recognized losses and carrying expense are separate quantities.
Reconcile before assigning a cause
Freeze the count time or account for movements during counting. Check receipts, sales, transfers, returns, unit conversions and adjustments. Recount material differences with an appropriate reviewer.
Distinguish known spoilage from an unexplained shortage. An expired item can have a documented disposal record; a missing case with no movement history needs investigation. A discount or markdown changes selling value and is not the same thing as missing physical stock.
When a supplier short-ships, record the actual received quantity and resolve the balance or credit. Entering the full ordered quantity creates phantom stock and makes the later count appear to show a loss that began at receiving.
Keep loss separate from demand
If a forecasting process infers use from count differences, unexplained shortages can contaminate the estimate. They do not automatically become customer demand in every system. Preserve reason codes and investigate missing movements before adjusting future buying rates.
LineNow stores explicit inventory adjustments and uses counts and movement history in its usage calculations. A buyer-entered decay assumption is for planning; it is not inferred automatically from every count variance or subtracted from actual on-hand without a recorded event. Check a received shortage, transfer and waste adjustment in the inventory workflow.