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Free tool Story point calculator.
Rate a story's complexity, uncertainty and effort, and get a Fibonacci estimate with the reasoning and whether to split it.
ComplexityHow hard is it to get right?
A few parts that must work together
UncertaintyHow much is still unknown?
A detail or two to check
EffortHow much work is there?
A day or two
5 story points: Medium
A comfortable size for a sprint.
A score of 2.75 out of 5, driven most by effort. A typical story: a few parts that work together, a few days of work.
Estimate it with your teamThe story point scale
What each number means.
Story points measure size relative to other stories, not hours. The gaps grow with the numbers, because the bigger a story, the less exact any estimate of it.
- 1
Tiny
A small, safe change: a label, a setting, a typo.
- 2
Small
Well understood and done within a day, with little to test.
- 3
Modest
Familiar work with a question or two to answer on the way.
- 5
Medium
A typical story: a few parts that work together, a few days of work.
- 8
Large
Most of a sprint for one person, or real unknowns: worth a look for a split.
- 13
Very large
Too much to finish safely in one sprint: split it before you commit to it.
- 21
Huge
An epic, not a story: break it into smaller stories and estimate those.
How the calculator works
No black box, just a weighted average.
The whole method fits on one card per step, so you can check any suggestion by hand.
Rate three factors
Complexity, uncertainty and effort, each from 1 to 5. Every rating says what it means, so two people mean the same by a 3.
Weigh them
Their weighted average is a score from 1 to 5, with effort 40%, complexity 35% and uncertainty 25%.
Place it on the scale
The score is spread evenly over the seven cards from 1 to 21 and rounded to the nearest: a score of 3 is 5 points.
Read the advice
From 8 points it suggests a split, and with uncertainty at 4 or 5 a short spike first.
Questions
What are story points?
A unit for the size of a piece of work compared with other pieces, taking in how much there is to do, how hard it is and how much is unknown. A 2 is about twice a 1; neither is a number of hours.
How does the story point calculator work?
You rate complexity, uncertainty and effort from 1 to 5. It takes their weighted average (effort 40%, complexity 35%, uncertainty 25%), spreads the scores from 1 to 5 evenly over the cards 1, 2, 3, 5, 8, 13 and 21, and picks the nearest.
Why do story points follow the Fibonacci sequence?
Because the bigger a story, the less exactly anyone can size it. The growing gaps between 1, 2, 3, 5, 8, 13 and 21 stop a team arguing over 9 or 10, when the honest answer is "about 8, maybe 13".
Should we use the calculator instead of planning poker?
No. It is a starting point for one person, handy before refinement or to check a hunch. In planning poker the whole team votes in secret, and the gaps between their votes bring out what one person would miss.
When should a story be split?
When it comes out at 13 or more, and often at 8. A story should fit comfortably in a sprint; split it by workflow step, by user role or by the simple case first, so each piece is still worth something on its own.
How many hours is a story point?
There is no fixed rate, and that is the point: each team settles its own scale by comparing stories. Over a few sprints, the points a team finishes per sprint (its velocity) tells it how much to plan.
How do we calibrate story points in a new team?
Pick a small story everyone understands and call it a 2 or a 3. Size every other story against it, and against the ones already sized, rather than in days. After two or three sprints the numbers settle.
Is the calculator free? Does it save my ratings?
It is free, with no sign-up. It runs in your browser: the ratings are not sent anywhere, and they are gone when you leave the page.