Kanban Charts Part I - Cumulative Flow Diagram

Kanbanize has plenty of powerful features presented in an intuitive and easy way, but one of the things that we are mostly recognized for is the powerful analytics module. We collect tons of statistical data and shape it to display a set of charts that anyone can use to optimize their business.

This post is one of a series dedicated to walk you through these charts and help you on your way to perfection.


Cumulative Flow Diagram

This is one of the most powerful tools available in the Lean world, and it is a pity that many people fail to recognize the value of this graph. Maybe an explanation like this is a good one to blame for this (sorry Wikipedia), but things are not so awfully complex when someone human explains it to you with some relevant examples. 

I bet you all know the stacked bar chart in Excel, right? If not, here’s an example with those ancient things that people used to enjoy centuries ago – books. On this chart, we show the books that we have read, that we are currently reading and the ones that we want to read, all of this in January, February, and March:

1 (2)

The concept is easy: each bar represents a value associated with a concrete moment in time (date, calendar week, a month of the year, year, etc) and each of the colors represents a different state (read, reading and to read).

This is a very basic example of a cumulative flow diagram (CFD). It is called “cumulative” because the values are accumulated over time. In our case, we start reading a book, then finish it and at the end, we add it to the pile of read books (we accumulate the books we’ve read). Since the number of books we’ve read can never go down, each consecutive bar is equal or higher than the previous, and never lower.

Now imagine how that chart would look like for a period of 3 years. In my case, that would be three horizontal lines, but someone who actually reads could get to something like the image below:

2 (2)

It’s a good-looking chart, but what does it say? Let’s try to figure it out.

This is how you read the chart as a normal person:

  • I have no idea what this means. Cut the crap and just read those books.

This is how you read the chart as a Leaniac (lean + maniac):

  • This guy is awfully slow.

Let’s try to figure out what’s on the Leaniac’s mind when they claim so bravely that the reader is slow.

When you “read” a CFD, you always start with the in-progress area (the orange area). In our case, it is constantly growing, which is the first problem we have. Some might argue that the yellow area is also WIP, but it depends on the context that we are in, so for the sake of simplicity I’d rather leave it out of the equation.

The first thing to remember when looking at a CFD:

Check if the work in progress area grows or rather stays constant over time. If it is constant or decreasing, you are most likely doing good, and if it is growing then you need to dig deeper. If work conditions (team size, project type, company environment) have not changed, but work in progress is growing, you may have an issue to deal with.

The second thing to check when looking at a CFD is how much is actually achieved. In other words, how steep the “Done” area is. If the team is very productive and well-suited for the job, they will be able to complete tasks quickly and the done pile will rapidly grow. On the other hand, if we fail to do a good job, then the done area would be flatter. If we are slower to deliver, then it means that our “Lead” and “Cycle” times are larger.

There are a million definitions of what Lead/Cycle time means, so you may want to go out there and search for the source of heavenly truth, but our definitions are very simple: Cycle time is the time you need to complete something you’ve started working on and Lead time is the time between the customer request and the delivery date. Let’s take an online store for example. The Lead time would be the time between the placement of the order and the time the product is delivered (the overall time). Each phase of the process would have a separate cycle time (cycle time of the processing of the order, the cycle time of the packaging of the product, the cycle time of the shipping, etc.).

The CFD does an amazing job visualizing your average lead and cycle times. It is simply the horizontal distance between “To Read” and “Read” for the lead time and between “Reading” and “Read” for the cycle time.

3 (2)

It’s amazing to see that in this example the lead time is more than three years (it is probably something like 5-6 years). Would you guess that without actually SEEING it here?

The second thing to remember when looking at a CFD:

Check how your average Lead/Cycle times are changing over time. Just draw a horizontal line between the To-Do / Done or In progress / Done and measure the delta in time. If they are growing, you are in trouble. If they go down, your customers are probably the happiest people on earth.

A quick example:

Let’s take our chart from above and measure the cycle time for each of the books we’ve read. We assume the following:

  • The person can read one book per month.

  • If the person reads more than one book at the same time, they spend equal time on each book throughout the month.

Scenario 1: There is no limit on the books in progress

2 (2)

The result:

The first book was finished in 3 months. The second in 6. The third took 9. The fourth was even worse: 16. The fifth is still in progress and is likely to take 20 months or so. The logic goes like that:

We start new books all the time (the orange area grows), therefore we have bigger amounts of work in progress. We have a lot of work in progress, therefore, we have longer (worse) cycle times.

The total number of finished books is 4.5.

Scenario 2: Only one book is allowed to be in progress at a time

4 (2)


Since we have a WIP limit = 1, each book that is started is finished. The average cycle time remains constant at 1 which is somewhat 20 times better than the previous situation.

The total number of finished books is 37, which is more than 700% improvement. All of this just because we have limited the books in progress to 1. Magic, isn’t it?

What to do if things went wrong?

Many of you who’ve just realized that they have a problem would ask for advice. Well, first of all, congratulations! Realizing you have a problem is the hardest step of all. What to do depends on the context, but it is always a good idea to:

  • Educate your peers and subordinates about the situation you are in. Never keep this kind of information for yourself;

  • Try to educate management about the same. Reality shows that many people work in companies where management does not understand Lean. These people are not stupid, they just need to be taught, and even if you think it’s not your job to do it, give it a try;

  • Sit together with your colleagues and analyze how things happened. Make it clear which practices are bad and have to be stopped. Keep the good ones;

  • Stop accepting new work until you finish what you have already started. Learn to say no when it is for the good of the company;

  • Agree on the maximum amount of work in progress that you can have at any point in time and hold everyone accountable if they break the agreement. Yeah, even management;

  • Look at your Kanban board and your CFD at least once a day. Make everyone look at it;

  • Endure the pain until you see things getting better. After that everyone will be on board.

Flow Diagram in Kanbanize


Kanbanize provides a Flow diagram for each Kanban board out of the box. You just create and move tasks while we do the rest behind the scenes. All charts in Kanbanize are interactive and here is what you can do with them:

  • hide/show some of the areas by clicking on the label in the legend below the chart;

  • choose which columns from the board to be included and you can also specify a date filter;

  • switch on the prediction engine, which takes into account your historical data and projects the most probable distribution of tasks in the future.

With that, we close the CFD chapter. We hope this post was useful to you and we would love to answer questions in the comments section below.

Happy Kanbanizing!

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One thought on “Kanban Charts Part I: Cumulative Flow Diagram

  1. Mauricio Gracia

    Hello Dimitar , this cumulative flow charts are really usefull, but how about burndown charts ? Are they supported by Kanbanize.com ? if so what steps need to be done

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