WIP limit
Definition
A WIP (work-in-progress) limit is a constraint applied to a Kanban board column that caps the maximum number of items allowed to be in that stage simultaneously, preventing overloading and forcing the team to finish existing work before pulling in new tasks.
WIP limits are the mechanism that transforms a Kanban board from a visual to-do list into a flow optimization system. The principle comes from Little's Law in queuing theory: the more work in flight simultaneously, the longer each item takes to complete.
Why WIP limits work: Context switching is expensive. Every time a person jumps from one task to another, they incur a cognitive switching cost. WIP limits force the team to concentrate on finishing rather than starting. Counterintuitively, limiting how many things are in progress speeds up overall delivery.
How WIP limits surface problems: When a column hits its WIP limit and work can't move forward, the team can't pull new work. This surfaces the bottleneck visibly and forces a conversation: what's blocking items in that column? The constraint makes dysfunction visible so it can be addressed.
Setting WIP limits: Start with 2n-1 (where n is the number of people who work in that stage) as a common starting rule. Adjust based on observation. A WIP limit that's never hit isn't constraining anything; one that's constantly hit signals a bottleneck that needs to be addressed.
WIP limits vs. capacity: WIP limits aren't about capacity planning — they're about flow. A team of three developers might set a WIP limit of 3 on the "In Development" column, which means on average each developer has one item in flight. But the point isn't to guarantee utilization — it's to prevent a pile-up.
Stop starting, start finishing is the Kanban mantra that WIP limits enforce.
Examples
- Column 'In Progress' has a WIP limit of 3 — when a fourth card arrives, the team stops to finish one of the three
- WIP limit violation flagged in team standup: 'Code Review' column has 5 cards against a limit of 2 — team swarms the reviews
- Team experiments with reducing WIP limit from 5 to 3 — cycle time drops from 4 days to 2.5 days
- New team sets WIP limit of 10 (effectively no limit) — learns nothing. Resets to 4 after coaching session
- Kanban board shows a swimlane for urgent items with a separate WIP limit of 1 to prevent urgent work from crowding out regular flow
Related terms
Snap a wip limit. Ship its actions.
BoardSnap turns any whiteboard — including this one — into a summary and action plan.