Burndown Chart Explained: Why the Ideal Line Lies

The short answer

A burndown chart has time on the horizontal axis and remaining work on the vertical axis. The line should trend down as work gets finished. A straight guideline from the starting amount to zero at the end shows the “expected” pace.

Use it to spot problems early: a flat line means nothing is finishing, a jump up means work was added. Do not use it to judge people. And do not expect the real line to follow the guideline, because real work rarely does.

What the chart shows

Atlassian’s burndown chart tutorial describes three common types:

The unit of work can be story points, story counts or task hours. Teams pick one and stay with it. Story points and counts are usually steadier than hours, which people tend to adjust each day.

The straight guideline (sometimes called the ideal line) runs from the total at the start to zero on the last day. It assumes equal progress every day, which almost never happens: work often finishes in lumps, because a story is either done or not.

Reading the shapes

According to the same Atlassian tutorial, these are the usual patterns and what they may mean. They are prompts for questions, not diagnoses.

A made-up sprint, day by day

All numbers are invented. A team starts a 10-day sprint with 40 story points. The guideline drops 40 ÷ 10 = 4 points per day. The table shows remaining points at the end of each of the first six days. On day 5, a stakeholder adds a 5-point story and the team finishes nothing that day, so total scope rises to 45.

Reading it. On day 6, 30 points remain against a guideline of 16, a gap of 14. But the gap hides two different things. Five of the 14 points are the added story, so scope explains part of it. The team has actually finished 45 − 30 = 15 points in 6 days, or 2.5 points per day.

Forecast. Four days remain. At 2.5 points a day, the team would finish about 10 more points, for 25 of 45 in total, leaving about 20 points undone. This is a rough projection, since the pace could change. It is a reason to talk now, not on day 10.

What the team can do. Options include dropping or deferring lower-priority stories, removing a blocker (the flat line on day 3 and the day with nothing finished are clues), swarming on one story at a time, or asking the stakeholder what comes out if the new story stays. The sprint goal helps decide which work matters most.

Note what the guideline did here. It stayed at 4 points per day even after scope grew, so it made the team look further behind than the work alone suggests. Some tools do the same, which is one reason a burnup chart can be clearer.

Burndown vs burnup

A burnup chart plots two lines: work completed and total scope. When scope grows, the scope line steps up, and anyone can see it.

In the example above, a burnup would show “completed 15, scope 45” at day 6. The team and the stakeholder see at once that the added story moved the scope line, not the team’s speed.

Build one in a spreadsheet

You do not need special software. Set up four columns:

1. Day: 0, 1, 2 and so on to the last day.
2. Guideline: total at the start, minus (total ÷ number of days) times the day number.
3. Remaining: enter the points still open at the end of each day, including anything added.
4. Completed (optional): total scope minus remaining, for a burnup line.

Then insert a line chart with Day on the horizontal axis. Update it once a day, at the same time, ideally before the stand-up so the team can discuss it.

Count a story as finished only when it meets your definition of done. Partial credit tends to make charts look better than the work is.

Where burndown charts mislead

A Scrum Alliance article, The Trouble with Sprint Burndowns, raises several problems, mostly with charts based on task hours. It is one author’s argument, not a rule, but the points are worth knowing:

• Hours can hide the truth. If people reduce remaining hours by the time they spent, not by what they think is left, the chart looks fine until late in the sprint.
• Chasing the line. Teams may try to match the guideline, though real work does not move in a straight line.
• Hidden work in progress. Many stories open at once can pile up in testing, and the chart does not show it.
• The wrong target. Tracking hours can pull attention from delivering working stories toward the sprint goal.

Atlassian’s tutorial adds that the chart does not show quality or value delivered, does not show scope changes clearly, and should not be used to rate individuals.

Better habits

• Count finished stories, not hours. Update only when a story is done.
• Keep stories small and similar in size. Then counts are meaningful and the line is smoother.
• Limit work in progress. Finishing one thing is better than starting five.
• Write a clear sprint goal. The goal tells you what to protect when time runs short.
• Review it with the team. Ask what the chart suggests, and what to try.
• Consider flow measures. Mature teams may track cycle time and work item age instead. See our guide to project management metrics.

Common mistakes

• Using it to rate people. It is a team signal.
• Letting it go stale. A chart updated twice a week hides trouble.
• Hiding scope changes. If work is added, say so and show it.
• Padding estimates to stay under the line. It defeats the purpose.
• Reading too much into one day. Look for trends over several days.
• Treating the chart as the goal. The goal is working product, not a pretty line.

Learn more

If you want structured study of agile planning and tracking, online providers such as Coursera and Udemy list project management and agile courses. We may earn a commission if you sign up, at no cost to you. We are not affiliated with any university. See our guides to agile, monitoring and controlling and the certificate in agile management for more.

Frequently asked questions

What is a burndown chart?

A chart that shows work remaining over time, usually within a sprint or toward a release, with a guideline showing expected steady progress.

How do you read a burndown chart?

Compare the actual line with the guideline. Above it can mean behind or added scope. Below it can mean ahead or overestimated work. Flat stretches suggest blocked work, and jumps up suggest added work.

What is the ideal line on a burndown chart?

A straight line from the total at the start to zero at the end. It is a reference, not a prediction, and real progress rarely follows it.

What is the difference between a burndown chart and a burnup chart?

Burndown shows work remaining. Burnup shows work completed and total scope. Burnup makes scope changes easier to see.

Is a burndown chart part of Scrum?

It is commonly used with Scrum, but as far as we know the Scrum Guide does not require it. Teams may use it as a transparency tool if it helps them.

Should a burndown chart use story points or hours?

Many teams prefer story points or story counts, because hour estimates are easy to adjust and can hide problems. Pick one unit and stay consistent.

How often should you update a burndown chart?

Daily during a sprint, ideally just before the team’s daily meeting, so the discussion uses current information.