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PR Size
Definition: PR Size measures the volume of changes included in a single Pull Request (PR). It is typically quantified by the number of lines of code changed (added + deleted), but can also be viewed by the number of files changed.
Why It Matters
PR Size has a direct and significant impact on the entire development workflow, affecting review quality, risk, and cycle time.
Impacts Review Quality: Large PRs are difficult and time-consuming to review thoroughly. This cognitive overload can lead to reviewers missing critical bugs or design flaws. Smaller PRs enable focused, high-quality reviews.
Correlates with Risk: The larger the change, the higher the risk of introducing an unintended defect. Small, incremental changes are safer and easier to troubleshoot if something goes wrong.
Affects Cycle Time: Large PRs take longer to write, longer to review, and longer to test. Keeping PRs small is one of the most effective ways to shorten
Cycle Time.
How to Measure It
PR Size is measured by analyzing the diff of a pull request from version control.
PR Size = Lines Added + Lines Deleted
It's also useful to track the number of files modified as a secondary measure of complexity.
Interpretation
Goal: The goal is to encourage small, focused PRs. There is no magic number, but many high-performing teams aim for PRs under 200-250 lines of code.
Look for Outliers: Identify and discuss outlier PRs that are exceptionally large. They often represent work that could have been broken down into smaller, independent changes.
Establish Team Norms: Use PR Size data to facilitate a team discussion and agree on reasonable guidelines. This is more effective than enforcing a strict, top-down rule.