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Kanban WIP Limit Calculator
Put each step of a process on a Kanban board, set a work-in-progress limit on every column, see the lead time the board implies, and spot the next bottleneck from weekly counts.
This tool also runs as a stage in a playbook, which takes you through several tools in order:
- Speed up a slow business process Stage 4 of 4: how do you stop work piling up again? Start at stage 1
Not following the playbook?
This stage builds on stages 1 to 3. Fix the constraint in stage 3 first, or choose your progress file under "Coming back?". You can also set up a board here on its own.
The columns, and what is in them now
- One column for each step, in order. Add one for a waiting state people usually leave out, such as "Waiting for the committee".
- Count what sits in each column right now, waiting or being worked on.
Items finished a week (optional)
How many items leave the last column in a normal week. With it, the tool works out the lead time the board implies.
Your notes never leave your browser
The columns and your counts stay on your computer and in your progress file. To write the diagnosis, only the counts and limits are sent to our server, by place in your list. How it works
Set a limit on every column
The limit is the most items that may sit in the column at once.
- Start each limit at about the number of items in the column today, then lower it a step at a time.
- When a column is full, the step before it stops starting new work and helps clear the queue instead.
The daily meeting
A short meeting at the board each day, starting with the column at its limit.
The board
Lead time, by Little's Law
Weekly board checks
Keeping the gain
Lead time, every week
On the map in stage 1: . Now: .
Then repeat from stage 2
Keep the map up to date: redraw it in stage 1 after each constraint is fixed, to see where the waiting moved.
Save your progress
Download your progress file to continue from this point any time, on any computer: choose it under "Coming back?" at the start of the tool. Each new file includes everything so far, including the earlier stages when they are connected, so keep the latest one. Your work stays in this browser only until you close it.
Not saved yet.
Take your results with you
A PDF of the board, the limits, the lead time and the diagnosis. In the playbook, the full report of all four stages.
About the tool
Why it exists
Keep the queue short once the constraint is fixed
A fixed constraint stays fixed only if work stops piling up in front of it again. Kanban makes the flow visible on a board, with one column for each step, and puts a work-in-progress limit on each column: the most items that may sit there at once.
This tool works on its own, and as stage 4 of our playbook for speeding up a slow business process, where the columns come from the value stream map of stage 1 and the constraint from stage 2. For the method, see our guide to Kanban.
The method
How the tool works
Limits start at today. Each limit starts at about the number of items in the column now, then comes down a step at a time. Limits that nobody ever reaches change nothing, so the tool flags a board with a lot of room.
Little's Law. Average lead time equals the items in progress divided by the items finished. With the items finished in a normal week, the tool shows the lead time the board implies now, and the most it could reach if every column filled to its limit.
Weekly checks. Count each column once a week. A column that is nearly full (90% of its limit or more) in most checks is where the next constraint is forming.
What leaves your computer. The column names stay in your browser and your progress file. To write the diagnosis, the page sends our server only the counts and limits, by place in your list, and the server keeps nothing.