What is a cumulative flow diagram?

A Cumulative Flow Diagram (CFD) is a cumulative diagram of task flow that shows how tasks move through process stages (for example: To Do → In Progress → Done). It visualizes the stability, speed, and bottlenecks in the team's work.

#Why it is needed

• helps see where tasks "get stuck";
• shows the balance between the input and output of tasks;
• allows measuring cycle time, throughput, and forecasting when work will finish.

#What it looks like

On the X axis - time, on the Y axis - the number of tasks. Each status (To Do, In Progress, Done) is shown as a separate colored band, and its thickness shows the accumulation of tasks.

• If the In Progress band grows, tasks are piling up and the team is overloaded.
• If the bands are parallel, the process is stable.
• If "Done" grows linearly, the team is releasing tasks at a steady pace.

#How to interpret it

• Band width = duration of the stage → lets you calculate the cycle time.
• Slope of the "Done" line = the speed of completing tasks (throughput).
• Widening band = delays or uneven workload.

#Conclusion

A Cumulative Flow Diagram is a tool for visual control of task flow. It shows how stable the process is, where the bottlenecks are, and how fast the team turns tasks into a finished result.