The number of lines of code that were added, changed or removed.
Why it matters: Typically, pull requests that are small are easier to review and get through the software development process faster. Each pull request also poses less risk because less is being changed at any one given time. Larger pull requests are more likely to get stuck in the review process and take up a lot of time from several engineers.
How to use it: When this metric is consistently high for an individual or team, it usually represents a coaching opportunity. During a coaching session, you may encourage a mentor to take a large pull request and work through how the solution may have been implemented in more incremental changes.
Note that it’s far easier to keep pull requests small than it is to break them down when they’re already large, so be on the lookout for any individual Pull Request that exceeds the team’s typical size, and consider helping team members merge them before they get too big.
You may see a difference in calculation between PR Size in GitHub vs. Velocity, and this is because GitHub shows raw lines added and Velocity shows relevant lines added.