Story point estimation

Story points vs. time

Hours depend on who does the work and on interruptions. Story points combine effort, complexity and uncertainty into one relative number. A story with 8 points is roughly four times as big as one with 2 points, regardless of who picks it up.

Relative estimation

Teams pick a well-understood reference story and compare new items with it: smaller, similar or bigger? Comparing is much easier for people than predicting absolute durations.

Fibonacci and other scales

The common Fibonacci scale is 0, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. The growing gaps reflect that big items are harder to estimate precisely. Modified Fibonacci (0, ½, 1, 2, 3, 5, 8, 13, 20, 40, 100), powers of 2 and T-shirt sizes (XXS–XXL) are popular alternatives. The “?” card signals that an item cannot be estimated yet.

When estimates differ

• A wide spread usually means different assumptions, not a wrong answer.
• Let the highest and lowest voters explain first.
• Clarify scope, risks and acceptance criteria, then vote again.
• Split stories that remain very large or very uncertain.

Reaching a shared estimate

The goal is a number the whole team can accept, not a mathematical average. onexip Scrum Poker shows the distribution, average and median after the reveal, which makes it easy to see whether the team already agrees.