Planning Poker Card Values Explained
Why does planning poker use 1, 2, 3, 5, 8, 13 instead of just 1, 2, 3, 4, 5, 6? What's the logic behind Fibonacci?
The gaps force meaningful distinctions. Between 1-2-3 the differences are small, perfect for small stories. But 5-8-13 gaps are bigger because larger stories have more uncertainty. You can't distinguish a "6" from a "7" reliably, but 5 vs 8 is a meaningful difference.
The non-linear scale matches how uncertainty grows with complexity. It's brilliant UX design.
It prevents false precision. If you had 1-10, people would debate whether something is a 6 or 7. With Fibonacci, you pick: is this closer to 5 or 8? Bigger jumps = faster decisions, less bikeshedding. The sequence enforces "rough order of magnitude" thinking.
Some teams add 0, 0.5, and ∞. 0 = already done, 0.5 = trivial config change, ∞ = too big to estimate (split it). We also have "?" card for "I don't understand the story enough to estimate". These additions help a lot.
Controversial: I think powers of 2 (1, 2, 4, 8, 16) work better. Simpler mental math, same concept. Fibonacci feels like cargo cult - works fine but not magic. Use whatever sequence creates the right gaps for YOUR team.