---
title: "Cumulative Flow Diagram"
canonical: "https://support.55degrees.se/space/SP/4343332869/Cumulative%20Flow%20Diagram"
format: markdown
---
Cumulative Flow Diagrams (CFDs) depict overall process stability. This chart uniquely displays the relationship among the three flow metrics: Work In Progress (WIP), Cycle Time, and Throughput.

![Screenshot 2026-06-02 at 11.20.45.png](media://80dbf5fc-1eac-4010-968a-452af222674b)

### How to Read the Chart

A cumulative flow diagram is a stacked area chart. The **vertical axis** represents the cumulative count of work items. The **horizontal axis** represents calendar days. Each **coloured band** on a CFD represents one workflow stage defined for your data. 

![Screenshot 2024-05-28 at 10.17.55.png]()

> ℹ️ **The CFD gives clues that must be looked into**
> ℹ️ 
> ℹ️ Looking at the colors to see how work flows and accumulates in your system generates lots of good questions to help uncover, not only how you use your workflow, but what issues lie within that keep you from delivering a steady flow of work. For instance:
> ℹ️ 
> ℹ️ - If one color bulges, it means work is entering that workflow stage but not moving out as fast. You might ask: "What is causing work to pile up here?"
> ℹ️ - If one color disappears, it means that all work has departed that stage, and no new work has entered it. You might ask: "Why have we stopped doing this workflow step?"
> ℹ️ 
> ℹ️ The "ideal" is to have parallel bands for all stages going up and to the right.

### Charts Controls

> Macro (refined-tabs)
> 
> > Macro (refined-tab)
> 
> This summary stats box gives you the following quick stats, based on the data you have selected:
> 
> - Arrival Rate (in items/day)
> - Throughput (in items/day)
> - Daily WIP (in items)
> - Cycle Time (in days)
> 
> This information is provided in a tabular format with rows representing each individual workflow stage but also one for the system (which is for your workflow as a whole). Please note that all values are calculated averages. 
> 
> ![Screenshot 2026-06-08 at 13.26.01.png](media://52fce606-ae51-4cb7-bd88-0b4977603f6e)
> 
> This panel updates as you filter or zoom in or out on your source data.
> 
> > Macro (refined-tab)
> 
> These are an easy way to glean some of the most important information from the CFD at a glance. It can tell you just by the slope of the lines if your system is stable. By stable, we mean, is the rate at which work enters your system (the top rate line) about the same as the rate at which it exits your system (the bottom rate line).
> 
> ![Screenshot 2026-06-08 at 13.26.26.png](media://e0b9c2ee-d5e1-452f-8d15-20d89eab81d5)
> 
> > Macro (refined-tab)
> 
> When the tooltip is enabled, you’ll see information for each stage and for the system as a whole, for each date as you hover it. The information includes:
> 
> - Cycle Time: The average cycle time for the system or a particular stage, as measured on that day.
> - WIP: It shows the number of items in the system or a particular stage on that day.
> 
> ![Screenshot 2026-06-08 at 13.27.04.png](media://117fb731-72e1-49ba-b5ee-d87f772b63d0)
> 
> > Macro (refined-tab)
> 
> This All Charts Control designates which Workflow Stages are considered [Not started] , [in progress]  and [finished] . Work items within each Workflow Stage will adhere to that sorting and count toward the calculations of Cycle Time, Throughput, WIP and Age.
> 
> ![Screenshot 2026-06-08 at 14.35.21.png](media://226543d8-c16d-411a-a6a1-40c5e3d66345)
> 
> The Workflow Stages are colour-coded so you can easily tell where the workflow starts and ends. Unchecking from the top down creates a later start, unchecking from the bottom up makes an earlier finish. Unchecking in the middle will merge your Workflow Stage with the one above - it will *not* remove or delete time spent in that Workflow Stage.
> 
> ![Screenshot 2026-06-08 at 14.35.53.png](media://63efce79-2614-4818-a452-777a45f3bc6e)
> 
> All workflow stages are visible in the top image below. The data for the yellow workflow stage shows 3 days and 6 items. 
> 
> In the lower image below, you see what happens to the data when we deselect the red workflow stage in the middle of the workflow. The data for this stage was added to the yellow workflow stage which reads 4 days and 12 items when previously the number of items was 6. The 6 from the red was added to it to make 12.
> 
> This is not a common usage of the Workflow Stages control.
> 
> ![Screenshot 2026-06-08 at 13.29.03.png](media://1b3d4d12-df53-4021-8f4e-3661cf1935bb)
> 
> ![Screenshot 2026-06-08 at 13.29.21.png](media://6e154a06-a604-48e8-8f3b-7c7ba3171041)
> 
> > ℹ️ Would you like to examine a specific section of your chart more closely? You can now zoom in without affecting any of the calculations activated when modifying the selected data for the chart. These small enhancements can greatly improve your analysis of complex data sets!
> 
> > Macro (refined-tab)
> 
> "Smooth" CFDs are really approximations of what happens between data points. To see a more realistic view of what is happening with your process data, uncheck the checkbox labeled: Smooth / Interpolate.
> 
> The button to toggle the Legend is here as well. The legend is on by default, but if you close it, you can come back here to show it again.
> 
> ![Screenshot 2026-06-08 at 13.30.15.png](media://7a217edf-619a-4e33-b4ca-c758492257d7)
> 
> ![Screenshot 2026-06-08 at 13.30.39.png](media://87d20ee9-3546-4171-ab7f-b97e1065d772)
> 
> ![Screenshot 2026-06-08 at 13.31.28.png](media://bd5f1870-54df-4fe5-a35a-4ceb374a7ba2)
> 
> > Macro (refined-tab)
> 
> To show the Data Control, click the symbol in the top right-hand corner of the chart, and it will appear below the chart.
> 
> With this control, you can further **narrow down the data included in the chart.** When doing so, the percentiles and summary statistics will be **re-calculated**.
> 
> All you have to do is click and drag over the desired time period and/or cycle time range, or use the date selector in the top-right corner of the Data Control.
> 
> > ℹ️ **Want to zoom in on the chart?**
> > ℹ️ 
> > ℹ️ You can zoom in on the cycle time chart itself, without triggering a re-calculation of percentiles and summary statistics.
> > ℹ️ 
> > ℹ️ If you use the Data control to zoom in, it will re-calculate those automatically.
> 
> ![Screenshot 2026-06-08 at 13.25.20.png](media://86698cda-417b-4931-a302-61cac9fce137)
> 
> ![Screenshot 2026-06-08 at 13.24.34.png](media://50244570-e815-4353-ba86-5c18c8740899)
> 
> > Macro (refined-tab)
> 
> If you would like to filter your data view by any attribute other than workflow stage, use the Item Filter control to manage what is shown in your data view. *Please note that the Data View "Raw (Source Data) is never affected by filters.*
> 
> Please see the Workflow Stages chart control below to see how using this control affects this data.
> 
> ![Screenshot 2026-06-08 at 13.32.18.png](media://e5930ef1-892b-4540-8bf6-d013d6b0bc86)

### How to Analyse the Data?

**Parallel lines** - *Lines staying the same distance apart.*

**Diverging lines **- *Lines getting farther away as you move to the right****.***

**Converging lines **- *Lines getting closer together as you move to the right.*

### What about Little’s Law?

A Cumulative Flow Diagram (CFD) provides a visual representation of Little's Law in action. By showing the relationship between Work in Progress (WIP), Throughput, and Cycle Time over time, the CFD helps you understand how changes in one flow metric affect the others.

Because these metrics are connected, changes in one often affect the others. For example, increasing WIP without increasing throughput will typically result in longer cycle times. Likewise, reducing WIP can help improve flow and predictability when throughput remains stable.

This makes the CFD a powerful tool for understanding flow. Rather than analyzing WIP, Throughput, or Cycle Time separately, you can see how they interact across the entire system.

For example, if work begins to accumulate in a workflow stage, the CFD bands will widen, indicating increasing WIP. If that trend continues, cycle times will often increase as work spends longer in the system.

By visualising all flow metrics together, the CFD can help you identify bottlenecks, imbalances, and emerging flow issues before they become visible elsewhere.

> ℹ️ Wants to learn more about Little’s Law? Daniel Vacanti wrote a series of articles about it. [https://www.55degrees.se/blog/post/littles-law-why-you-should-care](https://www.55degrees.se/blog/post/littles-law-why-you-should-care)