What is a Cumulative Flow Diagram?

As a visualization of the flow of work through a system, CFDs help teams identify bottlenecks, delays, and potential process improvements. They provide insights into work in progress (WIP), cycle time, throughput, and other key metrics that can help optimize workflow efficiency and predictability.

The difference between burn up charts and Cumulative Flow Diagrams is in their focus and the information they provide. They both show progress over time, but a burn up chart shows the total scope of work planned and work completed. In contrast, a CFD breaks down the workflow into multiple stages for a detailed view of where work items are in the process at any given time.

Another key difference is that burn up charts display two lines for this information, while CFDs use colored bands. Burn up charts are focused on the end result, and CFDs show the flow of work through the entire system, with an emphasis on visual indicators of process metrics like work in progress, cycle time, and throughput that are not clear in burn up charts. Teams interested in high-level reporting to stakeholders can use burn up charts, while CFDs are more valuable for teams that want to improve their process efficiency and identify workflow bottlenecks.

A Cumulative Flow Diagram is an instrument that provides essential insights into project workflow dynamics and team performance metrics and displays work in progress, cycle time, throughput, bottlenecks, lead time, and process stability. The diagram visualizes how work moves through a process over time to help teams make data-driven decisions.

• Work in progress (WIP): The vertical distance between bands shows how many items are in each stage.
• Cycle time: The horizontal distance between bands indicates how long work takes to move through stages.
• Throughput: The slope of the "Done" area reveals the rate at which work is being completed.
• Bottlenecks: Bands that widen indicate where work is accumulating in specific stages.
• Lead time: The horizontal distance from the entry point to the exit point shows overall delivery time.
• Process stability: Parallel bands indicate a stable, predictable workflow, while irregular patterns suggest inconsistency.

Teams that understand these metrics can optimize their processes, improve efficiency, and deliver value more predictably.

Reading a Cumulative Flow Diagram requires an understanding of its components and what the visual patterns reveal about a workflow. The horizontal axis represents time, while the vertical axis shows the cumulative count of work items.

The different colored bands that run from left to right represent various workflow stages (like "To Do," "In Progress," and "Done"). The wider a band, the more work benign done in that particular stage.

As more work is added, the upper slope of the diagram increases and shows the rate at which this is happening. Meanwhile, the lower slope of the "Done" band indicates the team's delivery rate or throughput. Healthy CFDs display more or less parallel lines between stages that indicate a smooth flow of work with consistent cycle times. Any sudden changes in the width of a band, unusual bulges, or flat sections can signal workflow problems worth investigating, such as process delays, scope changes, or resource constraints that may be impacting productivity.