Inventory shrinkage rate (ISR)

Inventory shrinkage is the unexplained or avoidable loss of stock between purchase or production and sale or use. It reduces availability and profit, distorts records and may raise customer prices, so the rate should lead to diagnosis rather than merely record loss.

When to use it

• Answer the key performance question: “To what extent are we losing inventory along our internal processes?”
• Use the KPI within the Operational processes and supply chain perspective.
• Define count boundaries, valuation, data sources, cadence and ownership before reporting it.
• Compare trends and like-for-like benchmarks, then investigate causes by location, item and process.

Origins

Shrinkage measurement developed through retail and warehouse control as organisations reconciled physical counts with book inventory. Barcodes, perpetual-inventory systems and loss-prevention practice made reconciliation more systematic. No single inventor is associated with the metric, and consistent definitions remain essential because theft, damage, waste, error and timing differences require different remedies.

What it is

Perspective: Operational processes and supply chain perspective.

Key performance question: To what extent are we losing inventory along our internal processes?

Shrinkage can result from breakage, spoilage, misplacement, receiving or scanning errors, supplier discrepancies, process waste, fraud and theft. Historic estimates have attributed about 44% to employee theft and 35% to shoplifting, but those proportions should not be assumed for a particular organisation or period.

The rate reveals the scale and location of inventory loss. Analyse it alongside adjustments, incidents and process observations so that controls address the actual cause instead of creating blanket surveillance or unjustified suspicion.

How to use it

Measurement

Choose whether to measure units, cost value or retail value. State the denominator and treatment of returns, write-offs, goods in transit and timing differences.