ISO 22400 KPIs that support inventory control are mainly the ones that show inventory levels, material flow, material losses, and execution reliability. They can help explain why inventory is building up, being consumed unpredictably, or becoming unusable. They do not, by themselves, prove inventory accuracy or replace ERP, MES, WMS, or QMS controls for stock status, lot traceability, reservations, or disposition.
Most relevant KPI areas
The exact KPI names and calculations depend on the ISO 22400 edition, the vendor implementation, and the site’s KPI catalog. In regulated manufacturing, the useful set usually includes these KPI areas:
- Inventory turns or inventory turnover: Shows how quickly inventory is consumed or converted. It is useful for spotting excess stock, slow-moving material, and mismatches between planning assumptions and actual consumption.
- Work in process inventory indicators: Help identify material trapped between operations, queues, inspection points, rework loops, or waiting-for-disposition states. This depends heavily on MES transaction discipline and routing fidelity.
- Finished goods ratio or finished goods inventory indicators: Show whether completed product is accumulating faster than it is shipped, released, or accepted. In regulated environments, “finished” must be distinguished from “released,” “accepted,” or “available to ship.”
- Throughput rate: Indicates how quickly material moves through production. Low or unstable throughput often drives higher buffers, expedites, and apparent inventory shortages.
- Planned order execution ratio: Shows whether production orders are being completed as planned. Poor execution reliability can create excess raw material, shortages at downstream steps, and misleading MRP signals.
- Planned order lead time and actual production time: Help compare expected flow time with actual flow time. This is important for setting realistic buffers, replenishment timing, and WIP expectations.
- Scrap ratio and actual-to-planned scrap ratio: Show material loss that directly affects usable inventory. These KPIs are only useful if scrap transactions are timely and tied to part, lot, operation, and cause codes.
- Rework ratio and first pass yield: Indicate how much inventory is temporarily unavailable because it is in rework, inspection, or quality hold. This matters because physically present inventory may not be usable inventory.
- Quality ratio: Helps separate produced quantity from conforming quantity. For inventory control, this distinction is often more important than the gross production count.
- Storage and transportation loss indicators: Where implemented, these help expose damage, handling loss, expiry, misplacement, or other losses that occur outside the value-adding process.
What ISO 22400 does not solve
ISO 22400 gives a common KPI structure, but it does not make inventory records correct. Inventory control still depends on accurate master data, bills of material, routings, units of measure, location logic, lot and serial tracking, and timely transaction capture.
Common failure modes include delayed backflushing, unscanned material moves, split lots, substitutions, unposted scrap, open nonconformance records, quarantine material counted as available stock, and mismatches between ERP financial inventory and MES shop-floor status. If those controls are weak, the KPIs may look precise while still being operationally misleading.
Brownfield system reality
In many plants, ERP owns financial inventory and MRP, MES owns WIP execution and operation status, WMS may own warehouse locations, QMS or MRB workflows own quality disposition, and PLM controls product definition and effectivity. Inventory KPIs are only credible when these boundaries are understood and reconciled.
Full system replacement just to standardize ISO 22400 reporting is usually unrealistic in regulated brownfield environments. Qualification burden, validation cost, downtime risk, interface complexity, traceability obligations, and long equipment lifecycles usually make mapping, data governance, and controlled integration the more practical path.
Practical use
For inventory control, ISO 22400 KPIs are best used as a shared measurement layer across operations, planning, quality, and IT. They should be tied back to source transactions and reviewed with clear definitions for “available,” “allocated,” “in process,” “on hold,” “scrapped,” and “released.” Without those definitions, the same KPI can drive different decisions in production, planning, finance, and quality.