Work-in-progress limits in Kanban

What it is

Kanban visualises the workflow as stages and limits the amount of work allowed in each stage or in the whole system. When a stage is full, the team helps to finish existing work instead of starting new work. The Kanban Guide describes the practices of defining and visualising the workflow, actively managing items in the workflow and improving the workflow, with flow metrics such as work-in-progress, throughput, work item age and cycle time.

Why it matters

Little's law links average WIP, throughput and cycle time: with stable throughput, more work in progress means longer cycle time. WIP limits are the lever teams actually control. They also make blocked work visible instead of hiding it in a growing "in progress" column.

How to apply

• Map the actual stages, including waiting stages such as "ready for review".
• Set a WIP limit per stage slightly below the current average, and lower it as flow improves.
• When a limit blocks starting new work, swarm on the oldest item or the bottleneck.
• Track work item age and cycle time; use them in reviews instead of estimates.

Pitfalls

Limits that are never hit are decoration. Counting items of very different sizes as equal hides variability; split large items. Personal WIP limits without team limits push the queue to the next stage.