Bucketing and its value

Bucketing is a process used during the estimation of stories to improve the relative baseline from which to measure the amount and complexity of work.

A common challenge in implementing Scrum is ensuring accuracy in estimation. Bucketing can have a significant influence on improving this accuracy. One of the main difficulties in estimation is establishing a proper baseline from which relative comparison can be performed. Bucketing addresses this issue. By comparing estimates, team members can calibrate their understanding of what a specific estimate represents. For example, building a CRUD system might be assigned a [1], and that baseline then informs the rest of the estimation.

Many teams use Fibonacci numbers for estimation. During kickoff meetings, the goal is typically to clarify stories enough to avoid assigning an estimate larger than [5]. Stories estimated as [5] or lower usually have enough clarity and transparency to allow accurate predictions of complexity and effort. Stories with estimates above [5] often indicate vagueness and many unknowns.

How Bucketing Works

Bucketing is most effective when applied after the initial estimation. Based on prior sprints, teams often develop a strong sense of what each estimate means in practice. For example, developers can usually agree on what a [1] entails. After all stories have been estimated, the backlog is reviewed one final time.

At this stage, “buckets” are created for each of the relevant Fibonacci estimates. Stories are grouped into these buckets, allowing for direct comparisons. For instance, a story estimated as a [1] can be evaluated against other [1]-estimated stories to ensure they involve a similar amount of work. Adjustments are made if necessary, resulting in a more accurately estimated backlog and improved velocity measurements.

Having a clear, shared understanding of what a [1] and what a [5] represents is critical. Ideally, the implication of each estimate in terms of complexity and effort should converge across teams. This consistency allows for meaningful comparisons of velocity between teams.

Supporting Practices

The INVEST criteria—which emphasizes stories being Independent, Negotiable, Valuable, Estimable, Small, and Testable—can further support this process. These criteria help create a mutual understanding of story scope and contribute to more reliable estimation outcomes.