Making Work Visible and Limiting What You Carry: The Kanban Idea

Kanban rests on two things: a visible board and a cap on work in progress

Kanban shows where each piece of work stands by putting it on a card, and it limits how many items you work on at once. It suits people whose tasks have outgrown their heads, or who keep starting jobs that never seem to finish.

The method began inside the Toyota Production System. Taiichi Ohno wanted each step to produce only what the next step had used, and cards (kanban means "signboard" in Japanese) attached to parts signaled when to replenish. The aim was to cut the waste of overproduction. David J. Anderson later brought the idea into software work and laid it out in his 2010 book Kanban. It is now used widely for knowledge work.

Building the board

Sticky notes work, as does any free board tool. Make three to five columns that match your stages:

• Ready (could be done)
• In progress
• Waiting (on a client's reply, or on your own review)
• Done

Each job gets one card, and you move it right as it advances. You can see at a glance where things stall. If cards pile up in Waiting, ask whether you lack a way to get replies or enough time for your own review.

Setting a work-in-progress limit

The biggest effect comes from capping the number of cards allowed in "In progress." Say three. When you hit the limit, you do not start anything new until something finishes.

There is a reason this helps. Little's law, from queueing theory, says average time in the system equals the amount of work in progress divided by the rate of completion. If your finishing pace stays the same, more items in progress means a longer wait for each one. Starting more things slows all of them.

Switching between jobs also costs effort, since you must remember where you left off. A limit trims that cost too.

Where it goes wrong

• You set a limit and then break it for every urgent request, so it becomes decoration.
• You add so many columns that updating the board is a chore.
• You build the board and never review it.

For urgent requests, decide the rule in advance, such as one reserved slot kept outside the normal limit. Treat the limit as adjustable: after a week or two, see whether work jams too much or you have room to spare, and change it.

Kanban shines most when work passes between several people. Working alone, the realistic benefit is that visibility and a cap reduce the habit of leaving things half done.

Naming and sizing the columns

Start with few columns. The more finely you divide the stages, the more tiresome updating becomes. Add a column when you feel a need, such as "too much is stuck in Waiting" or "I want to separate drafting from finishing."

Write each card as a unit of work that contains a verb. "Send A's quote" tells you when it is done; "A's project" does not. If a card sits for days without moving, it is probably too big, so split it.

Measuring the flow

Once you are used to the board, note on each card the date it entered In progress and the date it was done. Knowing how many days work takes shows you your normal pace. If you know roughly how long a certain kind of request takes, you can promise delivery dates with some basis.

You do not need fine data. Even an average number of days changes how you estimate.

Looking at the board for one minute at the start of each day helps the habit stick. Choose one or two cards to move today, and your priorities for the day become clear. At the end of the week, glance at the Done column; seeing what moved forward makes it easier to keep going. If you share work with a contractor, let them see the same board so that requests and replies are visible to both of you.

What to do next

1. Write every job you are holding on its own card.
2. Arrange the cards in four columns: Ready, In progress, Waiting, Done.
3. Set the In progress limit to three for now.
4. When you reach the limit, finish one job before starting another.
5. After two weeks, look at where cards sit longest and adjust the limit or the columns.