Burn down charts: how to read a sprint at a glance

A burn down chart plots the work left in a sprint day by day against an ideal line. How to read its shapes, what they do and do not tell you, and how Prior draws it.

6 min read

A burn down chart shows how much work is left in a sprint, day by day. The line should fall toward zero by the last day. If it sits below the ideal line, the team is ahead. If it sits above, the team is behind.

#What it is

It is a standard tool of Scrum teams. The Scrum Guide mentions burn-downs, burn-ups and cumulative flow diagrams as ways to forecast, and says that none of them replaces empiricism: you still decide from what has actually happened.

The chart has two lines on a grid. The horizontal axis is the days of the sprint. The vertical axis is the work left, usually in story points. The ideal line is straight, from the work committed on day one down to zero on the last day. The actual line is what really remains. With story points, work leaves the line only when a story is finished, so the actual line moves in steps.

#Why it works

A burn down chart is a progress monitor that the whole team can see. In a 2016 meta-analysis of 138 experiments with 19,951 people, Benjamin Harkin and colleagues found that prompting people to monitor their progress toward a goal improved goal attainment (d+ = 0.40), and more so when the progress was physically recorded or reported publicly (Psychological Bulletin). Most of the studies were about personal health goals, so the fit is an inference, but it is the same mechanism: when progress is in front of you, you adjust sooner.

Timing is the second reason. A team that sees it is behind on day 3 can split a story or ask for help. A team that finds out on day 9 can only drop work.

#How to read it

Compare the actual line with the ideal line, then look at its shape.

These are common readings, not rules. The chart tells you where to look. Only the team can tell you why.

A burn up chart draws two lines in place of one: the work done, which rises, and the total scope, which is a line of its own. When someone adds work, the scope line steps up and you see it. In a burn down chart, added work and finished work cancel out on the same line, so a flat stretch can mean either. A burn up chart keeps them apart, which makes it easier to read when the scope changes.

Take a team with 40 points committed over 10 days. The ideal line says 20 points should be left on day 5. The actual line says 31. The team looks at its board and finds two 8-point stories in progress, both waiting for review. They finish one, split the other, and by day 8 there are 14 points left against an ideal 8. At the sprint review one 5-point story is left, and the team moves it out of the sprint with the product owner's agreement.

#How to use it

#Mistakes to avoid

• Treating the ideal line as a target. Real work is not linear. A line that sits a little above the ideal in the middle is normal.
• Letting stories stay in progress. Many half-done stories give a flat line and a cliff. Finish before you start.
• Changing estimates to flatter the line. Re-sizing work mid-sprint hides what the chart is there to show.
• Hiding scope changes. If work is added, say so. A burn up chart shows it.
• Using the chart as a report card. A chart used to judge the team makes people stop reporting honestly.
• Leaving stories unestimated. The chart cannot count what has no size.

#When it is the wrong tool

• In continuous flow. With no sprint, there is nothing to burn down. Look at how long items take, or at a cumulative flow diagram.
• For very small sprints. With five stories, the line moves in a few large steps. Count the stories.
• When nothing is estimated. Count issues instead. Prior does this for you.
• When the target is a long fixed deadline. A burn up chart for the whole release shows scope and progress over months.

#In Prior

In a Scrum project, open the Sprints tab. The Burn chart sits above the sprint cards.

• Pick the sprint. It starts on the running sprint, or on the last finished one.
• Switch the view. Burn down | Burn up.
• Burn down draws Remaining work (scope minus done) and a dashed Ideal line from the scope committed on the first day to zero on the last day.
• Burn up draws Done, the total Scope, which steps when work is added or removed, and the Ideal line from 0 up to the committed scope.
• Today is marked, and days to come are empty, with only the ideal line reaching the end.
• Unit. The chart counts story points when any issue of the sprint has an estimate. Otherwise it counts issues and says In issues (nothing estimated).
• Details. Hover or tap a day for its values, and use the arrow keys when the chart has focus. A screen reader gets a one-sentence summary and a hidden table of every day.

The chart reloads when an issue of the sprint changes state, points or sprint.

Two limits to know. For a project saved on Prior's servers, the chart replays the history of your tasks, so each day shows the points and completion those tasks had that day. Sprint membership has no history, so the scope is the sprint's current issues: an issue you remove from the sprint also disappears from past days, and one added late shows from the day it was created, not the day it joined. For a personal project, or when Prior cannot reach the server, the chart is built from the tasks as they are now and is marked Estimated: a completed issue counts on the day it last changed, and re-estimates are not known.

See Burn charts for the reference, and Cycles and sprints for the sprint setup.