Velocity is defined as the average amount of the Product Backlog a team can turn into an Increment of Done. In essence, it is a measure of capacity to create something that is potentially releasable in a single Sprint.
The Definition of Done serves a number of purposes:
Some teams count the number of items they can deliver to Done in a single Sprint.
Many teams use the Planning Poker technique (an adaption of Wideband Delphi) with a modified Fibonacci scale or “t-shirt sizes” to assess the size of work.
Add up all of the story points for items that have achieved the Definition of Done by the end of the Sprint. This is their velocity for that Sprint.
Due simply to natural variability, velocity will vary from Sprint to Sprint. A great Scrum Master will help the team record and identify:
This helps everyone understand what can potentially be Done in any given Sprint given clear and transparent history of what the team has turned into an Increment of Done, not on what the Product Owner demands based on deadlines.
1. Sutherland, J. and Schwaber, K. (2020) The Scrum Guide. The Definitive Guide to Scrum: The Rules of the Game.