What is a work-in-progress limit on a board column?

## What the number on the column means A **work-in-progress limit** is a whole number written against a column of a team's work board. It caps how many cards may sit in that column at the same moment. If a column called *In review* carries a limit of three, then three cards is the most that column may ever hold - a fourth cannot be moved in, however small it looks, however senior the person who wants to start it, and however close a deadline is. Two words in that definition carry the weight. - **Cap.** The number is an upper bound, never a quota to fill. A column holding one card under a limit of four is perfectly healthy; a column holding five under a limit of four is a breach the team has to resolve, not a good week. - **Moment.** The limit counts cards present right now. It says nothing about how many cards the team finished last week, and it is not an allowance handed to each person. A 7-person team can run a board whose columns total four in flight, and teams often should. ## Why it has to be a hard rule A number that bends on request is not a limit; it is a wish. All of the value comes from what happens the instant a team reaches it: the column refuses the next card, and that refusal has to be answered rather than waived. The refusal is the only moment when a team is forced to look at why the cards it already has are not finishing. Remove it - by raising the number whenever it is inconvenient - and the board goes back to being a picture of everything that has ever been started, which is the state it was drawn to escape. This is why the limit is best described as an **explicit constraint on the system** rather than a rule about people. Nobody is being told to work less. The team is being told that the way to move a card in is to move a card out. ## Stop starting, start finishing The behaviour a cap produces has a slogan: **stop starting, start finishing**. In practice it means that when a person becomes free, the first question is not *what should I pick up?* but *what is already in progress that I can help finish?* Helping might mean reviewing a colleague's change, chasing the approval a card is waiting on, producing the missing test data, or pairing on the hardest part of somebody else's card. The slogan matters because instinct runs the other way. Starting feels productive: it is visible, it is entirely under your own control, and it converts an awkward free hour into apparent progress. Helping finish someone else's card feels like assisting rather than working. The cap removes the choice - with the column closed, the only route to new work runs through the cards already open. ## Where the number is written Placement changes what the limit constrains: 1. **Per column** - the common default; each active stage carries its own number. 2. **Across a stage and its queue** - one number covering a working column plus the waiting column that feeds it, so the queue cannot swell to hide a delay behind an apparently healthy stage. 3. **Across the whole board** - a single number for everything in flight, useful for small teams and for boards whose columns change often. 4. **Per person** - rare, and it tends to recreate the problem the board exists to expose, because the unit becomes each individual's busyness rather than the team's finished work. ## What a limit is not | Device | What it constrains | What happens at the boundary | | --- | --- | --- | | Work-in-progress limit | cards in a column at this moment | no card may enter until one leaves | | Capacity forecast | how much the team expects to finish | the forecast is revised; nothing is blocked | | Priority order | which card is taken next | a different card is chosen | | Timebox | how long a period runs | the period ends and work carries over | Confusing the first row with the second is the most common early mistake. A forecast is a prediction and can be wrong without anything stopping. A limit is a rule the board enforces, and reaching it is normal, expected and useful - a limit that is never reached is telling the team nothing at all. ## What it looks like on a real board A 7-person team building a legal-document review product might cap analysis at three, build at four and legal check at two. On a good day nothing blocks and cards move steadily. On a normal day one column fills, somebody who wanted to start a new card cannot, and that person goes and helps at the column that is full. Nothing dramatic happens; the team simply spends its slack on finishing instead of on starting. Over weeks the effect compounds: fewer things are open at once, and each of them closes sooner.