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Fibonacci Scale:
A classic sequence for all purposes

Parabol fibonacci estimation scale

Inspired by the world of mathematics 


One of the most popular scales used in Sprint Poker is the Fibonacci scale, which is based on the Fibonacci numbers – a sequence where each number is the sum of the two preceding numbers, starting from zero.

So that would be 1, 2, 3, 5, 8, 13, 21, 34 and so on. 

In Planning Poker or Sprint Poker, the Fibonacci numbers appear on your hand of cards, starting at 1 and going up to 34 – and don’t forget there’s a question card and a pass card as well.


Fibonacci-Sprint-Poker-Scale (1)


Why use the Fibonacci Scale?


What’s nice about the Fibonacci scale (aside from Fibonacci being fun to say) is that it promotes high-level estimation.

Because the numbers are integers, there are no half steps or tricky granular distinctions. No one is going to rate something a 1.5 for example.

But the numbers are closer on one end of the scale, so it’s not completely devoid of granularity. As a result you’ll be able to go into more detail for small tasks, and have greater breadth of choices for large ones. And that fits the nature of estimating large tasks – because many times you just don’t know all the details.

The way the Fibonacci scale grows in a lagging exponential is its unique strength. It manages to capture the knowns and unknowns that make sizing small and large tickets easy:

For small tasks you’ll generally be able to estimate any issues, so more granularity on that end of the scale makes sense.

For larger tasks it can be more difficult to pinpoint how much effort something requires, so the numbers (and the distance between them) grow to accommodate that. 

That’s the magic of the Fibonacci sequence, it’s not just the numbers, but the spaces between them, that help you size your tasks.


Going full Fibonacci in Parabol

To use the Fibonacci scale in your Sprint Poker meeting, simply select it as your scale when you start the meeting.

Each participant will get 10 cards. Eight of the cards will have your Fibonacci sequence, one will have a question mark, and the other is a pass card.



The question mark card is useful to signal when you’re stumped on a task. If you don’t have enough information to make an accurate estimation, or you just aren’t sure where it lands, you can play that card. After the facilitator reveals the cards, you can discuss how to turn that question mark into a number or if more information is needed to do so.

The pass card is for passing on an estimation. This can be useful if you’re on a multi-disciplinary team, where not every task will require each discipline. So if you had front-end development and design on the same team, a designer could pass on estimating a task that would be going straight to the front-end team. 

The Fibonacci scale is just one of the sizing options you can use when estimating with Parabol’s Sprint Poker tool. There’s also the T-Shirt Sizes scale and the Five Fingers scale.

Or you can even make your own scale – how about mouse, hamster, guinea pig, opossum? It’s up to you!

Try it yourself with a free account 


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