Why Planning Poker Uses the Fibonacci Sequence

Planning Poker decks follow the Fibonacci sequence — 1, 2, 3, 5, 8, 13 and so on — where each number is the sum of the two before it. The growing gaps are not a gimmick; they mirror how uncertainty grows with size.

What is the Fibonacci sequence?

The Fibonacci sequence is a series where every term is the sum of the previous two: 1, 2, 3, 5, 8, 13, 21. In Planning Poker, a modified version is printed on the cards, often with a 0, a ½ and a coffee-cup "I need a break" card alongside the numbers.

Why use it for estimation?

Large items are inherently harder to estimate, so fine-grained choices like 14 versus 15 are meaningless. The widening gaps force a clear decision — is this a 5 or an 8? — and stop the team wasting time on false precision. The scale itself encodes the uncertainty of bigger work.

Estimating with a Fibonacci deck

Each member picks the Fibonacci card that best matches the relative effort of a story, then everyone reveals at once. If votes are far apart — say a 3 and a 13 — that gap is a signal to discuss before voting again. RevealSprint ships a Fibonacci deck ready to use.