Definition
A WIP limit (Work In Progress limit) is the maximum number of work items allowed in any single stage of a workflow at one time.
Why WIP limits matter
Without WIP limits, work piles up in whatever stage is slowest. The pile grows invisibly. Cycle time worsens. People keep starting new work because finishing existing work feels stuck.
With a WIP limit, the pile becomes visible immediately. The limit is hit, no new work can enter the stage, and the team is forced to either help clear the bottleneck or address the upstream cause.
Example
A repair shop runs Intake → Diagnosis → Repair → QA → Ready. They set a WIP limit of 5 on Repair. If 5 jobs are already in Repair, no new jobs enter Repair until one moves to QA. If diagnosed jobs start piling up waiting for Repair, the team knows immediately that the bottleneck is the bench, not intake.
Common WIP limit pitfalls
- Setting them too high. If the limit never bites, it's not a limit — it's decoration. Start tight; relax only with data.
- Bypassing them. "Just this once" turns into "always." The whole mechanism breaks.
- Not visualizing them. The current count vs. the limit must be visible on the board.