Now, when you know the size of work you need to know your capacity. The capacity, also known as velocity, is how many story points your system can complete during a certain time period, for instance a week. To get the velocity you also need to estimate the work you completed during the last weeks.

With both, the total size of a project and a velocity, you can calculate how long the project will take to complete.

Let's say the sum of all the work in the project is estimated to 200 story points and your capacity is 20 story points per week. Easy math will tell you that the project will take 10 weeks to complete. The result has more value than the traditional way of guessing before the project has started. It's based on real facts and if people are always too optimistic when estimating it will be reflected in the velocity so the calculation will be correct anyway.

The most important thing is not to have an estimated release date, especially...