Application of Velocity while planning the project, releases, sprints

If there are 50 features to be developed to complete the product, then how many sprints do we need to plan?. To answer this question we need to;

  1. Estimate the story points of the features in the product backlog. Let us say, the sum of the story points of the 50 features in the product backlog comes to 100.
  2. To complete this 50 features, how many sprints do we need?. Here based on our expert judgment we may have to make some decisions based on assumptions like;
    1. Every sprint we can complete 10 story points worth of work. Then we say planned average velocity = 10.
    2. If the average velocity is 10, then we need 10 sprints of 30 days to complete 100 story points.
  3. In this case, if we are planning only sequential sprints, the project will take approximately 10 months to complete (10 sprints of 30 days each)
  4. If we want to deliver the product of the project in lesser than 10 months, then we whould plan for parallel sprints.

Application of velocity during the execution phase of the projects

Actual Velocity = Number of story points completed during a sprint (iteration)

For example, for Sprint#1, the planned story points=10. At the end of the sprint one, the team achieved on story points 9. Then the actual velocity = 9. So, for the second sprint, instead of planning 10 story points, the team has to plan only 9 story points.

At the end of the second sprint, if the team has achieved 11 story points instead of 9, for the third sprint the team would plan for 11 story points. At the end of the third sprint, if the team has achived 11 story points, then the average actual velocity will be;

(9+11+11)/3 = 10.33

The balance story points to be accomplished / average velocity will always give an indication of the number of sprints required to complete the release or the product.