A Cumulative Flow Diagram after a week of activity
The Cumulative Flow Diagram (also known as a "burn-up chart" or the "cumulative input-output diagram) is a graphical representation of an Epic's number of Stories over time, grouped by Workflow State. When used correctly, your Cumulative Flow Diagram can help you track changes as well as identify (and unblock!) bottlenecks.
The Cumulative Flow Diagram in Clubhouse is located in the "Reports" tab that can be accessed by clicking into the Epic. Note that your Cumulative Flow Diagram will only be available if Stories have been added to the Epic you are viewing and your Epic has been moved to In Progress.
Reading the Cumulative Flow Diagram
A Cumulative Flow Diagram after several months of activity
The x-axis of the Cumulative Flow Diagram represents time from Epic start date to today's date, while the y-axis measures the number of Stories in the Epic and how the number of Stories in each Workflow State has grown/shrunk. The x-axis will start at the date when the Epic was moved into the 'In Progress' state.
Note that the Cumulative Flow Diagram will always display in number of Stories, even if your Organization has its Estimate Scale set to "Show Progress and Metrics Using Estimate Points" in Settings > Estimate Scale.