What is a Cumulative Flow Diagram?

The setup of the Cumulative Flow Diagram is quite simple. Color-coded bands represent different stages of workflow. The vertical axis of the Cumulative Flow Diagram shows how many tasks are in each stage of the workflow process, while the horizontal axis displays these tasks over a given period of time.

Information such as backlogged tasks, work in progress, and work completed are easily seen within the diagram. Moreover, the Cumulative Flow diagram can provide deeper insight into potential problems and disruptions in the progress. This insight can be used to make adjustments to the process.

There are many different scenarios that can occur when reading a Cumulative Flow Diagram. Ideally, bands on a Cumulative Flow Diagram should move parallel with each other as tasks are completed and new tasks are started. As the bands continue to run parallel, the band of “completed tasks” should continue to grow.

A widening of a band indicates the number of assignments coming in are greater than those completed. This will most likely lead to delays in the process. When this occurs, there should be a focus on finishing the work in progress (or WIP) before others are started.

A Cumulative Flow Diagram that shows narrowing of bands suggests the productivity in one stage is too concentrated and should be distributed in other areas to allow for better workflow.

The total amount of WIP can be found by drawing a vertical line from the top of the “completed” lane to the uppermost lane. To calculate the average throughput, a horizontal line can be drawn from a given point on the edge of the “completed” lane. When the horizontal and vertical lines are connected to form a triangle, one can determine how quickly tasks are getting done.

Cumulative Flow Diagrams can be beneficial to teams as it provides a clear visualization of workflow and understanding into how projects are progressing. Areas of concern are easily identifiable as the diagram widens or narrows.

When a problem area is easily detected, changes can be made so that work can continue efficiently.

Cumulative Flow Diagrams can also show the total amount of WIP (work in process) and how quickly projects are being completed.

This allows teams to determine if they are on track and gives them the ability to project when projects will be completed on time and when they will not.

A Cumulative Flow Diagram provides clear, quick visual insight into the flow of productivity in a system. It can be used to calculate burn-up trajectories for work, as well as to aid in identifying problems that may be forming within the process.

Using a flow-based system like Kanban, it is essential to keep a steady flow of work moving through your processes. Using tools like the Cumulative Flow Diagram will help you deliver more value, faster, and with more insight, to your customers, partners and internal stakeholders.