What is a burndown chart?

A burndown chart is a visual representation of how an agile team is working towards a deadline, detailing the work left to do versus time remaining.

In the Scrum framework (an Agile methodology), work is completed by small, cross-functional teams, where tasks are planned and executed in short cycles typically lasting no more than four weeks in length. During these sprints or iterations, the team works together uninterrupted, acting as its own authority on how much work should be completed during the cycle. The burndown chart helps teams visualise their progress within the sprint, using a simple line chart drawn between time and work remaining.

The burndown chart illustrates briefly whether the sprint is moving ahead as planned, or whether the team will need to make certain adjustments to hit the established goal. More specifically, it helps teams accomplish the following:

Reporting estimated effort for tasks

Completing a project or sprint within a deadline demands a clear understanding of how much effort will be required. Burndown charts clearly represent the estimated effort remaining for uncompleted tasks, which teams can then use in their reporting. By visualising and analysing remaining effort, teams can more easily make changes where necessary to reach their objectives.

Visualising the progression of work

One of the greatest advantages of a burndown chart is its simplicity; the chart is easy to understand, and teams benefit from using it as a progress tracker. By visualising the progress (or lack of progress) on specific projects, teams can make course corrections and re-evaluate processes in real time.

Burndown charts are not the only visualisation tools within the Scrum methodology. Burnup charts share a similar coordinate system to burndown charts but shift their focus away from what is left to do, to what work has already been done.

In a burndown chart, the amount of work to be done lessens, resulting in a decrease towards the right.

Conversely, in a burnup chart, the amount of work to be completed is depicted as one straight line across the top of the graph, while a second line is used to track work completed. The burnup chart starts at zero and increases towards the right as teams complete their tasks.

Put more simply, a burndown chart depicts what’s left, and a burnup chart helps visualise what’s been accomplished. Burndown charts are often the simpler approach, combining completed work and total work into a single line that moves towards zero as the project progresses. Burnup charts are slightly more complex, separating work and total work out as two individual lines on the graph. This provides a clearer, more informative picture of the realities of the project, helping teams identify specifically where problems may be occurring.

Graphic displaying the difference between burndown charts vs. burnup charts

Although relatively simple to construct and easy to read, burndown charts nonetheless provide several clear advantages, even when compared to more detail-intensive burnup charts.

Probably the most obvious benefit of the burndown chart is that it offers a clear snapshot of project progress. It gives agile teams an easy-to-follow visual representation of how the sprint is going, acting as a status report, and showcasing the most important data to help ensure that everyone involved is on the same page.

Burndown charts also assist in planning and tracking. They offer a clear view into the progress of the project—its speed, acceleration and any slow patches that may arise. This not only improves reporting and analysis, it also helps teams create more accurate plans and goals for future projects.

Likewise, an effective burndown chart helps teams identify issues as they occur. When the work stalls, team members can coordinate to locate and resolve root causes before they become significant problems. This reduces the risks involved in projects, increasing the likelihood of achieving favourable outcomes.

Finally, burndown charts promote effective communication. By creating a simple graphic detailing progress on the project, collaboration and communication becomes easier.

Just as one of the greatest advantages of the burnout chart is its simplicity, this lack of complexity can also create challenges. The burndown chart represents how many story points have been completed over a given amount of time, but it is incapable of measuring or showcasing the overall scope of work.

For example, a burndown chart can identify changes, but cannot distinguish between changes that are a result of completed items, and those that stem from increasing or decreasing the number of story points. In these cases, a burnup chart may be a more effective approach.

As previously stated, the burndown chart takes the form of a simple two-line graph. The timeline is displayed along the bottom x-axis, and the y-axis is the remaining effort needed to complete the project. The two lines represent the following:

Ideal work

This should be a straight line descending from the right to the left, connecting the start point (day one) to the end point (deadline). The line starts at the top of the y-axis and terminates as it crosses the x-axis at the point of the deadline, indicating that there is no more work to be done and no more time in which to do it. This is an ideal line based on estimates and is seldom completely accurate. Instead, it represents a simplified projection of project progress.

Actual work remaining

The actual work line begins at the exact same location as the ideal work (day one, all tasks remain to be completed), but will likely fluctuate up or down as the sprint progresses. Each day, as tasks are completed, a new point is added to the line moving to the right towards the deadline date.

As the chart develops, comparing the two lines provides insight into how well the project is progressing; if the actual work is below the ideal work line, then there is less work remaining to be done than anticipated for a given day, and the project can be said to be ahead of schedule. If, on the other hand, the actual work line is above the ideal work, then there are more tasks remaining than expected, and the project is behind schedule.

Although this setup represents the most-basic burndown chart, it can be further detailed by adding the following elements:

  • Scope forecast
    The possibility of scope change based on historical data
  • Remaining forecast
    Prediction of the burndown for future dates; indicates whether the sprint can be completed by the deadline, based on historical data.

ServiceNow, a world leader in IT service management, provides the tools and resources for organisations to create effective, powerful burndown charts. The ITBM Agile 2.0 Sprint Dashboard allows users to clearly visualise and track story progress. The dashboard incorporates a variety of widgets, including Scope, Percent Completed, Time Elapsed, Committed Points, Blocked Work, and Missing Estimates.

By incorporating detailed and easy-to-read burnup and burndown reports and using the resultant information to create a cumulative flow diagram, the Agile 2.0 Dashboard provides essential insights into the project’s current state. This includes scope changes and trends, how much work has been completed and how much still needs to be done, total number of stories, number of stories that may be missing estimates, likelihood of completing the sprint by the deadline and more. With these insights, teams can better understand the ideal pace of work, how much work is remaining and if the scope is likely to be completed before the end of the sprint.

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