Guide
Estimation scales for planning poker
A planning poker scale is the set of cards a team is allowed to choose from. The scale matters more than it looks. Too many options invite false precision, and too few make every story look the same. This guide covers the common scales, what story points are, and how to pick one.
Story points
A story point is a relative unit for the size of a piece of work. It combines effort, complexity and uncertainty into one number, and it is not a number of hours. A team decides what a 1 or a 3 means by comparing stories: "this one is about twice the work of that one we finished last sprint".
Story points only mean something inside one team. A 5 on one team is not comparable with a 5 on another, and points are not a way to compare teams or measure individual people. Over a few sprints, the total of points a team finishes gives it a rough velocity it can use to plan.
Fibonacci
The Fibonacci sequence (1, 2, 3, 5, 8, 13, 21) is the most common planning poker scale. The gaps grow as the numbers grow, which matches how estimates behave: a team can tell a 2 from a 3, but nobody can honestly tell a 20 from a 21. The widening gaps push the team to pick a side instead of arguing over a small difference.
Use it when the team already thinks in story points, or when you want a default that works for most backlogs. It is the first preset in Spooky Planning.
Modified Fibonacci
Modified Fibonacci (0.5, 1, 2, 3, 5, 8, 13, 20) adds a half point at the bottom and replaces 21 with 20. The half point is useful for tiny changes such as a copy edit or a config tweak, which would otherwise all be rounded up to 1. Spooky Planning includes it as a preset.
T-shirt sizes
T-shirt sizes give up numbers for small, medium and large. They are a good fit for early planning, roadmap sessions, or a team that is new to estimating and does not want to argue about numbers yet. They are quick, and they avoid the false suggestion that a story of 3 is exactly three times a story of 1.
The trade-off is that sizes cannot be added up. A team that needs a sprint forecast will usually convert sizes to points later. The T-Shirts preset in Spooky Planning has S, M and L, and you can create a scale with more sizes.
Powers of Two
Powers of Two (2, 4, 8, 16, 32, 64, 128) is a scale in which each card is double the last. It suits work that is roughly measured on a doubling scale, and teams that like to keep only a few clearly different sizes. It is a preset in Spooky Planning.
Custom scales
Sometimes none of the standard scales fits. A team might estimate in days, in ideal hours, or with a short list of labels of its own. In Spooky Planning you can create a scale with a name, choose whether its values are numbers or text, and enter the options as a comma-separated list such as 2, 4, 8, 16, 24. A preview shows the cards before you save. You can edit or delete your own scales later, and pick any of them when you create a room.
Every room also has two extra cards that are not part of any scale: a question mark for "I do not know enough to estimate this" and a coffee cup for "I need a break". They are left out of the average.
How to choose
- Not sure where to start? Use Fibonacci.
- Lots of tiny changes? Try Modified Fibonacci.
- New to estimating, or planning a long way ahead? Use T-shirt sizes.
- A team convention that no standard scale covers? Make a custom scale.
- Whatever you choose, keep the scale short. Seven or eight cards are plenty, and you can change the scale between sprints if it is not working.
Reading the result
After the votes are revealed, the room shows the average of the numeric votes and an agreement level, which is the share of players who chose the most common card. The average is a starting point for the conversation, not the answer. If the votes are 3, 3, 5 and 13, the useful information is why one person voted 13.