Estimation
The practice of forecasting the size, effort, or duration of Product Backlog items to support planning.
What it means
Estimation is not mandated by the Scrum Guide, which leaves sizing techniques entirely up to the team. Common approaches include story points, t-shirt sizes, and ideal hours.
Estimates support forecasting and conversation, not commitment. Treating an estimate as a guarantee tends to produce padded numbers and defensive behavior rather than useful planning input.
Common mistakes
Some teams practice #NoEstimates, focusing instead on breaking work into small, similarly sized items and tracking cycle time, avoiding estimation overhead altogether. This is not part of official Scrum but a recognized alternative practice.
Example
During Refinement, the team estimates five backlog items using Planning Poker before Sprint Planning begins.