Scrum: Sprint Burndown Chart

Sprint burndown is a graphical representation of the estimated effort-hours remaining for a given period of time during a Sprint. Plotting the total effort-hours remaining for each incomplete task on a given day, on a graph, results in the sprint burndown chart which is significant for communicating progress as shown below.

The horizontal axis of the sprint burndown chart represents the days within a sprint, whereas the vertical axis represents the remaining estimated effort-hours. The chart should be updated every day to exhibit the total estimated effort remaining across all the uncompleted tasks.

What does a sprint burndown chart depict?

• Total estimate of the efforts in hours in a sprint
  It is the calculation of total work in hours for User Stories and other work items which the team is committed to.
  
  
• Total amount of effort remaining in a sprint
  This is what sprint burndown chart depicts and this is why this graph got its name which simply means “effort burndown chart”. Every day the team will burn down some effort, so definitely no work effort remains on last day of the sprint.
  
  
• Total number of working days in a sprint
  The graph shows this because it is essential for a team to estimate and thoroughly work on the committed work every day. In fact, this is nothing but your sprint duration
  
  
• Ideal Effort
  It is drawn by evaluating the accurate amount of effort remaining which needs to be burnt down by the team in a sprint. This serves as a reference for a team and this is why we see it as a very straight line from the top of Y-axis to X-axis.
  
  
• Real Effort
  Real effort line shows the effort remaining. This line varies from day to day and team to team as it completely relies on the effort remaining every day. For instance, if more items are added once the sprint started, this appears as an upward spike. Similarly, the line comes down on finishing the tasks every day.

How to read a sprint burndown chart?

Fig: Sprint Burndown chart with trend lines

The three burndown lines that are overlapped as shown in the figure above demonstrate distinct situations.

• If the trend line intersects the horizontal axis close to the end of the sprint duration, we can conclude that we have completed all the tasks “on time”.
• If it lands to the left, we can infer that we have finished the tasks “Early” and should probably check whether we can securely adopt extra work.
• If it lands to the right, it means we are “Late” in finishing, either because we have taken a lot of work or we are not continuing at the expected pace or both. At this point, we should explore more to perceive what’s behind the data and what went wrong.

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