Kanban guide · Flow and metrics
WIP Limits in Kanban: How to Set and Use Them
A work-in-progress (WIP) limit caps how many items can be in a stage of your workflow at the same time. It is the single most powerful practice in Kanban: limiting WIP shortens delivery times, exposes bottlenecks and reduces overload.
Key takeaways
- WIP limits cap how much work is in progress in each stage.
- By Little's Law, less WIP means shorter cycle times at the same throughput.
- Start slightly below current WIP and adjust with data.
Why limiting WIP works
Little's Law, a result from queueing theory published by John Little in 1961, links three flow measures: average cycle time = average WIP ÷ average throughput. If a team's throughput stays the same, halving work in progress roughly halves the time each item takes. Fewer items in progress also means less task switching, faster feedback and problems that surface sooner.
Types of WIP limits
| Type | Example | Use |
|---|---|---|
| Per column | Develop: max 4 | Most common; controls each stage |
| Per person | Max 2 items each | Prevents individual overload |
| Per swimlane | Expedite: max 1 | Protects urgent capacity; see swimlanes |
| Whole system (CONWIP) | Max 12 items between commitment and delivery | Simple start for small teams |
Setting your first limits
- Count how many items are currently in each column.
- Start with a limit slightly below today's level, or about one to two items per person working in that stage.
- Add the limits to the column headers so they are visible.
- Run for two to four weeks and watch where work waits.
- Lower limits gradually where queues form; raise them only if people are idle for structural reasons.
When a column hits its limit
- Don't start new work in that column.
- Help finish or unblock items downstream; see swarming.
- Look at the cause: is a later stage the bottleneck?
- Discuss repeated limit breaches in your next review rather than ignoring them.
Common mistakes
- Setting limits so high they never bite.
- Breaking limits whenever someone asks, without discussion.
- Ignoring waiting columns, where most delay often hides.
- Treating limits as fixed forever instead of experimenting.
Free templates for this topic
Frequently asked questions
What is a good WIP limit?
There is no universal number. Start with roughly one to two items per person in each active stage, then adjust based on cycle time and where work queues.
Can a team break a WIP limit?
Occasionally, for genuine emergencies, but every breach should be visible and discussed. Frequent breaches mean the limit or the process needs to change.
What does WIP mean in a WIP limit?
WIP stands for work in progress: items that have been started but not yet finished.
What is a WIP limit?
A WIP limit is the maximum number of items allowed in a column, lane or the whole workflow at one time. When the limit is reached, the team finishes work before starting more.
Why are WIP limits important?
They reduce multitasking, expose bottlenecks and shorten cycle time. By Little's Law, average cycle time equals average WIP divided by average throughput, so less WIP means faster delivery at the same throughput.
How do you calculate a WIP limit?
There is no exact formula. A common starting point is about the number of people working that stage, or slightly fewer, then lower it gradually while watching cycle time and blockers.
What happens when a WIP limit is reached?
No new items can be pulled into that stage. Team members help finish or unblock existing work, which is often called "stop starting, start finishing".
Should the Done column have a WIP limit?
No. Done is the end of the flow, so it is not limited. Limits apply to active and waiting stages where work accumulates.
What is Little's Law and how does it explain WIP limits?
A queueing theory result published by John Little in 1961: average cycle time = average WIP ÷ average throughput. It explains why limiting WIP shortens cycle time.
Do WIP limits slow teams down?
They may feel slower at first, but they usually shorten the time to finish each item and raise predictability, because work is finished rather than left half-done.
Can you use WIP limits per person?
Yes. Personal limits, such as no more than two items each, are common and help in personal Kanban, though column limits better reflect team flow.