The real purpose of Kanban is continuous improvement.

Glancing at a Cumulative Flow Diagram (CFD), used along with Kanban, lets you spot all sorts of issues your team may be facing-nice background material for a discussion on process improvement.

But you have to understand the chart first.

Let’s start!

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1. Kanban Board and Input Data

Required activities to support the cumulative flow diagram

For the CFD to be useful and accurate, your team must perform the following activities for keeping up to date the source of its raw data.

Once you’ve downloaded and set up the spreadsheet with kanban board and embedded CFD here, during the daily standup (physical or virtual) you’ll add new cards to the ‘KanbanBoard’ sheet for every new work item, or move the existing ones accordingly to their stage of completion,

and record that date (the ‘timestamp’).

Then, you’ll enter a new row on the ‘TrackingData’ sheet for every new card.

Once more, make sure to adjust the formulas in columns E and O with the new cell reference. E.g.:

=transpose(KanbanBoard!$N$41:$N$50)

The existing rows on the ‘TrackingData’ sheet updates automatically whenever a kanban board card is pulled to the next stage. 

Finally, you’ll update the kanban board sheet daily, but for the CFD I used the granularity of a week. So, the sheet ‘WeeklySummary’ is the final data range on which the chart is built upon. Check that its formulas run correctly but don’t edit anything on it. It just aggregates the daily input on weekly intervals, based on the timestamps you record daily on the kanban board card and re-arrange in tabular format on the ‘InputData’ sheet.

‘Timestamp’ is a paramount concept here.

In order to draw a CFD, you need to know the number of work items you have in each step of your board per day. But instead of tracking that by counting them and gathering the data manually in a table, I followed Richard Brenner’s brilliant approach of timestamps.

It complicates things a little but it lets you put further analysis on this data which you can’t when you only count the items. So, we were saying, instead of counting the items on the board in every column every day during the standup, you put dates on the tickets when they enter a state you want to track and this formula on the ‘WeeklySummary’ sheet counts the items of the workflow for you:

=IF(TODAY()>=$B10,COUNTIFS(TrackingData!$G$10:$G$1000,"<="&$D10,TrackingData!$H$10:$H$1000,"="&""),"")

That’s it!

The cumulative flow chart on the ‘CFD’ sheet updates automatically without any manual edit (whenever you enter a new task or pull an existing one on the board sheet).

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2. Cumulative Flow Diagram

What is a Cumulative Flow Diagram

A CFD is a common graph used together with Kanban.

It’s an area chart that shows the accumulated number of work items for every status in a flow.

The CDF is so popular as a visualization tool that has been defined as the successor to the Scrum burn-down chart.

For example, you can use the information it provides for project planning, since the done curve is a burn-up. Or, you can measure how efficiently your team is delivering value by measuring the horizontal distance between the curves. On the other side, the vertical distance between the curves tells you what’s wrong with your flow.

How to Read a Cumulative Flow Diagram

The  CFD helps you analyze the flow of your process by measuring vertical and horizontal distances within the chart.

1. The vertical y-axis indicates the cumulative number of work items (i.e. cards) in the workflow at any point in time.
2. The horizontal x-axis indicates the time frame for which the chart is visualizing data.
3. The curves are basically a number of items in any possible workflow status (i.e. a column on your board itself) shown cumulatively in a time perspective. Meaning that the CFD shows the way the tasks mount up column after column (in our case: to do > analyze > work > verify > done.).

What a Cumulative Flow Diagram Tells You

A CFD shows the following metrics:

1. Lead Time

Lead time refers to the time taken to finish the complete process, from idea to finished feature in production.

You can calculate the lead time for each story by measuring the total horizontal length of the colored area in the diagram, at any given date, from the beginning to the last curve.

2. Cycle Time

Cycle time points to the time a work item takes to go through part of the process—for example, doing development and testing.

In the graph, the cycle time for parts of the process measures the horizontal difference between the top and bottom lines at any point along the CDF.

3. Work in Progress – WIP

The hight of each colored band on the graph represents the amount of work in progress (WIP) in each state.

The horizontal distance between the lines of the first band shows the size of your backlog (the number of items in the Inbox). The height of all the areas down to Done measures your total WIP at any given date.

4. Throughput

Throughput is the rate at which the process produces completed work items. 

Throughput on the sample CFD is the number of completed work items per week, and it’s visualized by the angle of the completed work items line (the line between the red and the blue areas). The steeper the slope, the more productive a team in completing tasks quickly.

Sample cumulative flow diagram with 4 metrics: lead time, cycle time, WIP, and throughput.

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3. Cumulative Flow Diagram: Next Steps

Ideally, the CFD should smoothly slope upwards, without breaks, jumps or flat periods – as that indicates a smooth flow of the project.

Here are a few  links you may want to check out to learn more about the common scenarios a CFD presents you and  what should you do if your CFD is less than smooth:

• Check out my post “How to Smash Time to Market with Kanban Metrics: 3 Cumulative Flow Diagram Scenarios“
• Learn more about CFD in this book by Daniel S. Vacanti: Actionable Agile Metrics for Predictability: An Introduction, and in this paper by Karthik Karunanithi: Metrics in Agile and Kanban, Software Measurement Techniques.
• Learn more about CFD wonders for Kanban teams in this text by Joakim Sundén and Marcus Hammarberg: Kanban in Action.
• Check out my free kanban board spreadsheets for Excel and Google Sheets.
• Keep up-to-date with new agile and kanban freebies by subscribing to my YouTube Channel.

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