What is a burndown chart?
A sprint burndown chart is a graph that shows the amount of work completed in a given interval versus the amount of work that was expected to be completed in the same period. In other words, the burndown chart shows the actual rate of completion of a project against the projected rate of completion for a given sprint. This then becomes an information radiator showing the latest information.
The present performance is known as the burndown rate. A burndown chart shows this burndown rate clearly and makes it easy to estimate if the task will be completed on time. These charts are also seen from the perspective of work that’s yet to be done versus time. Based on this the team can decide to take any necessary steps to speed up the process and make any changes needed.
Here, the rate at which a scrum team progresses is known as the velocity. This is a measure of the number of story points completed in a sprint. Only stories that are actually completed are included in this velocity.
Burndown charts are mostly used in agile methods such as scrum, but can also be used to estimate the performance of any project. The exact metrics used in a sprint burndown chart would differ based on the team and project. However, the basic idea of work done/ left to be done vs work expected to be done remains the same.
Parts of a burndown chart
At the end of the sprint, the aim is to complete all the remaining tasks or to clear the backlog. ‘Burning down’ means doing so, ie, completing the backlog until there’s no work left. The parts constituting a burndown chart are the same you’d expect to see on most X-Y graphs. These are:
- The X-Axis - representing the estimated time. Units could be hours, days, etc.
- The Y-Axis - represents the amount of work that has been done or work that’s yet to be done depending on the perspective of viewing. Units could be the number of tasks remaining or number of story points/ work hours.
- Progress Line - This shows the way your team is progressing in a given sprint. The data is updated in real time and the line shows whether your team is able to meet the targets in a given sprint.
- Guideline - This is the ideal progress line. It represents the ideal way that your team should perform in the given sprint. The closer your progress line is to the guideline, the better your team’s performance.
Both the progress line and the guideline show the total story points that are assigned to issues and requests under the milestone. The burndown chart automatically reflects the completed work as issues are closed. Let’s understand this below.
Who handles the chart?
Agile teams are not very big and as such, all the team members have a responsibility to handle the burndown chart. This involves creating and updating it. These people responsible for the chart are the development team, the product owner and the scrum master.
It is the duty of the development team to show the information about the work being done to the product owners in a transparent way. Based on the way the progress line fares against the ideal line, the product owner then makes decisions about the product. This decision is mainly whether the product is still good to be released on the expected date or if there’d be any changes to the expected release date.
The third party, the scrum master, is responsible for ensuring that the team follows the agile scrum principles. The scrum master supports and coaches the team in this pursuit.
What does the chart show?
The following entities are represented in the burndown charts:
- Total estimate of efforts
The total number of work hours that the team has committed to. It is obtained by summing the efforts in hours in user-stories, tickets and issues.
- Effort remaining
The sprint burndown chart shows this overall. On each day of the sprint, some work is burned down to make sure that there’s no pending work on the last day.
- Total working days
This is the sprint duration. It’s meant to give the team an idea of how much work to do every day based on the results that they’ve committed to.
- Ideal effort
This component is based on the ideal line. It gives an idea of the exact work that a team is to do in a given interval to reach the goal in the expected time. The ideal straight line gives a great idea of the amount remaining to be burned down.
- Real effort
As you would have guessed, this shows the actual performance and the effort remaining to be put in by the team. It varies between teams and days as it depends on the amount of effort that is added or reduced on the previous day.
How to read a burndown chart?
If you’re familiar with graphs, then by now you already know how to read the sprint burndown chart and what you can understand from it. However, here’s a quick overview of how to go about reading a Burndown chart.
Keep in mind that the Burndown chart shows how close the team is to the expected schedule of completing tasks. As such, we are going to read it based on how well the team has been able to stick to the schedule itself.
- Behind schedule
When the progress line is above the guideline, it shows that the team is behind schedule. Your team should have completed more work by this point.
- Ahead of schedule
When the progress line is below the guideline, it shows that the team is ahead of schedule. Your team is likely to hit the target before the estimated end date of the sprint. It’s likely that the tasks were overestimated and you can consider adding more tasks to the sprint.
- On track
When the progress line and the guideline are close or overlapping, this shows that your team is on track and will hit the target on time.
How to create a burndown chart?
Now that you have all the information you need to understand what a burndown chart is, it’s time to create one for your team. The following four steps will help you do so with ease. You may wish to use units other than the ones mentioned.
- Estimate the work to be done - this would be your Y-axis in units of story points/ tasks.
- Estimate time available for completion - this would be the X-axis in days/ hours/ sprints.
- Estimate the ideal effort to be put in - this would be the idea line.
- For example, if you’ve got a 100 story points, then the number 100 on the Y-axis would be the point to mark.
- On the X-axis, this would be the point where all work is estimated to be completed. So, if you feel it would be completed in 5 days, the 5 day mark would be the point.
- Draw a diagonal line through these two points.