Inventory drift

Inventory drift is the gradual mismatch between the inventory quantity recorded in a system and the actual quantity physically available on the shop floor, in stores, or in transit. It commonly appears when small transaction errors accumulate over time.

In manufacturing, inventory drift can affect raw materials, work in process, finished goods, tooling, spare parts, or serialized components. Typical causes include missed issues or returns, unrecorded scrap, incorrect counts, late system updates, unit-of-measure errors, substitution without proper transaction history, or poor synchronization between ERP, MES, warehouse, and shop-floor systems.

Inventory drift is related to inventory accuracy, but it describes the movement away from accuracy over time rather than a single count result. It should not be confused with planned inventory adjustment, safety stock, or normal consumption. In regulated or traceability-sensitive operations, drift can also create gaps between material records, production execution data, and physical availability, even when no single transaction appears significant by itself.