Work In Progress Limits in the Kanban Method

Limiting work-in-progress is one of the core practices of the Kanban method. The work-in-progress (WIP) limits play an essential role in ensuring a swift flow of work by enforcing the transition from a push to pull system of work. The WIP limits serve as guardrails for enacting the well-known Kanban mantra of “stop starting and start finishing”.  Depending on where the WIP limits are placed in our Kanban system, they drive different benefits.

• WIP limits per column/workflow stage – help achieve a smooth flow across the stages of the workflow and allow detecting bottlenecks. If the workflow spans across multiple teams, the column WIP limits naturally protect individual teams from overburdening themselves.
• WIP limits per swimlane – allow us to allocate capacity to categories of work items, e.g. work item types or classes of services.
• Personal WIP limits – protect individuals from overburdening.
• CONWIP (CONstant WIP) - a single WIP limit on top of the entire Kanban system (i.e. also above all other WIP limits) introduced to achieve customer (requestor) pull. The CONWIP represents the number of tokens available to the customer and which are attached to requests as soon as any work on the item starts. A new request will be started processing only when there is a free token available.

These different kinds of WIP limits can be used at the same time in a single Kanban system. In such cases, the total of the swimlane WIP limit should be equal to the total of the column WIP limit.