Little’s Law for Production Flow

For a stable system, average work in process equals average throughput multiplied by average flow time: WIP = throughput × lead time.

Worked example

A cell averages 24 units of WIP and ships 6 good units per hour. Its average flow time is 24 ÷ 6 = 4 hours. Use one boundary and the same time period for all three measures.

What it does not prove

Little’s Law does not explain a queue’s cause or promise that reducing WIP will preserve output. Check variability, rework, blocking, capacity, and the physical process before changing limits.

Use the WIP and kanban calculator · Download the OEE production log template