On this burndown chart, the height of each bar represents the amount of work remaining in the release. This figure shows a release with 175 Story Points planned in it as of Sprint 1.
The team finished 25 Story Points in Sprint 1, leaving 150 to go as of the start of Sprint 2. There were 120 Story Points as of the start of Sprint 3. So, the top of the bar is reduced by the amount of work the team finishes in a given Sprint.
Before the start of Sprint 4, the Product Owner added new Stories to the product. This additional work is shown at the bottom of the bar for the fourth Sprint. You can see that the vertical height of Sprint 4 goes from about -40 to about 95, or 135 Story Points of work remaining. Forty of those 135 Story Points are from new work.
Prior to the start of Sprint 6, Stories were removed by the Product Owner. As with an increase in scope, a decrease in scope comes off the bottom.Â
One way to forecast how many Sprints a team will take to get to a release will take is to draw a trend line through the bars and extend the baseline.