Work out wip limit instantly with clear inputs, formula shown and shareable results.
Little's law fixes the relationship: WIP = throughput x lead time. To hit a lead time target at a given throughput, WIP must be capped at their product. Any WIP above that cap adds queue time without adding output, which is why current lead time can be read straight off current WIP.
Little's law
WIP = throughput x lead time; lead time = WIP / throughput
Station cap
WIP per station = WIP limit / number of stations
Not until WIP falls below the level needed to keep the bottleneck fed. Above that, extra WIP only lengthens queues. The productive range is usually far lower than intuition suggests.
At the release point into the line. Capping release is what actually controls WIP; capping downstream just moves the queue.