Many have asked why Fibonacci series is used for the story point estimates. Though I agree, it is not the only way to estimate based on relative sizing and many of them use different methods, this one is used frequently.

In this article, I would like to shine your memory to understand the fundamentals behind using the Fibonacci series. And you won’t even need a deck of cards for this one.

Let’s take an example where you are asked to hold a weight of 2 Kgs

If the weight is increased by .02 Kgs i.e. 2.02 Kgs is the total weight, it would be very negligible to notice the difference by the person who lifts the weight especially when he is unaware that it was increased by 0.02 Kgs.

The same is true when a person is asked to lift the weight of 5 Kgs and then it is increased by 0.05 Kgs without him/her getting noticed, the person wouldn’t feel the increase in the weight.
Weber in 1834 realized that there is a particular threshold and the ratio, the background intensity to the incremental threshold is relatively constant.

In the equation, K is constant.



Coming back to Fibonacci sequence in this series, an accurate estimate would be 1, 2, 3, 5, 8,13,21,34,55…

However, this series is modified in Agile estimation world as 1,2,3,5,8,13,20,40…

Each estimator is modified just for the sake of easiness of use of 20,40,80 and 100.

As you understand from the above sequence, it is clear that 2 is 2 times bigger than 1, however, the gap between 3 to 5 or even between 5 to 8 is not double. These nonlinear sequences work well in the high-level estimates as they reflect great amount of Uncertainty. This will prevent one user story to be too close to another.

The user stories that would be worked out in upcoming PI planning, it is better to be estimated within one order of magnitude.

Enjoy using the planning poker with the above-mentioned series and get better in your high-level estimates.

Agile Estimating and Planning Poker Sessions

How does this and theories of planning poker cards relate to Agile Training? The Estimation process for instance can be used as part of the planning technique when seen fit. Sprint planning is often an example of this where the solution is ironed out during the progress and changes from initial estimates, but the basic path is largely accounted for initially.  Whether scrum poker, even traditional poker with a deck of playing cards or another estimation technique, the same baseline principle is behind each iteration.

From product owners and shareholders to consultants and execs, software development teams, advertising teams and more, learn how your team members can become more agile teams and Schedule a Consultation with us today. Leadership Tribe specialize in agile development and training courses for your entire team to help you streamline the planning process and make it a more functional team today.