When and How to Re-Estimate Stories
Know when to update story point estimates during a sprint or across sprints. Covers scope changes, dependency discoveries, and estimation confidence decay.
Detailed Explanation
When and How to Re-Estimate Stories
Estimates are not promises. They are forecasts based on current knowledge, and knowledge changes. Knowing when to re-estimate prevents sprint disruptions and keeps velocity metrics honest.
When to Re-Estimate
1. Scope changes mid-sprint
If the product owner adds or changes acceptance criteria after planning, the estimate must be revisited. A story that was a 5 with three acceptance criteria might become an 8 with five.
Original: "Display user profile" (3 pts)
- Name, email, avatar
Updated mid-sprint: "Display user profile with activity feed"
- Name, email, avatar, last 10 activities, pagination
→ Re-estimate: 8 pts
2. Undiscovered dependencies
You start a story and realize it requires a database migration, a library upgrade, or coordination with another team that was not anticipated.
3. Technology surprises
The library you planned to use does not support your use case. The API behaves differently in production than in docs.
4. Carry-over from a previous sprint
If a story was not completed and carries into the next sprint, do not keep the original estimate. Re-evaluate: has anything changed? Is the remaining work less than originally estimated?
When NOT to Re-Estimate
- Do not re-estimate just because it took longer than expected. The story was what it was. Adjusting after the fact corrupts velocity data.
- Do not re-estimate to "look better." If velocity is low because estimates were accurate but the team hit blockers, that is a process issue, not an estimation issue.
How to Re-Estimate
- Bring the story back to the team. Do not let one person unilaterally change it.
- Compare the new understanding to the reference story: "Is this still a 5, or has it become an 8?"
- Document the reason for the change in the story's notes.
- Adjust sprint capacity accordingly. If a 5 became a 13, something else may need to be moved to the backlog.
Impact on Velocity
Re-estimation is tracked as the new estimate for velocity purposes. If a story was re-estimated from 5 to 8 and the team completes it, 8 points count toward velocity, not 5.
Use Case
Reference this guide when a story's scope changes mid-sprint and the team is unsure whether to re-estimate or simply accept the variance.