Burndown Charts: How to Read and Build Them, with Burnup Examples
与謝秀作
A burndown chart plots remaining work against time. Dates or working days run along the horizontal axis; remaining points or items run along the vertical axis. The line usually moves downward as work is completed.
Read the line alongside scope changes, the completion standard, and the update schedule. It shows work remaining, not whether the product solves the customer’s problem.
Burndown versus burnup
Chart | Main lines | Useful question |
|---|---|---|
Burndown | Remaining work | What is left before the end of the period? |
Burnup | Cumulative completed work and total scope | Is the gap changing because of delivery or added scope? |
GitLab’s official documentation explains both chart types and their treatment of work and scope. A burnup chart is particularly useful when total scope changes frequently.
A worked example
Assume 20 points initially and five working days. All numbers below are fictional. Remaining work equals initial scope plus cumulative additions minus cumulative completions.
Day | Added to date | Completed to date | Remaining | Original ideal line |
|---|---|---|---|---|
Start | 0 | 0 | 20 | 20 |
1 | 0 | 3 | 17 | 16 |
2 | 0 | 7 | 13 | 12 |
3 | 5 | 10 | 15 | 8 |
4 | 5 | 18 | 7 | 4 |
5 | 5 | 25 | 0 | 0 |
On day three, the team completed three points, but five points were added. Remaining work rose from 13 to 15. That does not mean no work happened. A burnup chart would show total scope rising from 20 to 25 while completed work rose from 7 to 10.
Build the chart in a spreadsheet
- Define the period and one measurement unit. Do not mix points and hours in one series.
- Record the initial item list and total scope.
- Record additions, removals, and completions at a consistent time each day.
- Calculate remaining work and plot it as a line against dates.
- Add an optional ideal line and annotate scope changes.
For a simple ideal line, use initial work × (1 − elapsed working days ÷ total working days). Here it falls by four points daily. This is a reference line, not a requirement for people to finish equal amounts every day.
When scope changes, decide whether to retain the original reference or replan. Record the change and its date. Silently rewriting history hides the explanation for the chart’s movement.
Interpret patterns carefully
A flat line can mean large items, review queues, testing delays, or stale records. A sharp late drop can mean work genuinely finished together or that updates were postponed. Investigate before concluding that the team is behind.
Being below the ideal line is not proof of success either. Removing scope or marking items complete before required checks also reduces the remaining total. Read the chart with the Sprint Goal and completion criteria described in Sprint Duration and Planning.
Connect current progress with future planning
Agile Velocity uses completed work across Sprints to support future forecasts. Burndown helps the team discuss adjustments during the current period. Item counts can be used, but disclose the unit and consider differences in item size.
When progress affects campaign costs or approvals, keep those decisions visible too. Xtrategy’s project management features connect task progress with cost and approval information in the project context.