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PR Time to Merge ​

Definition: PR Time to Merge measures the total time a Pull Request (PR) remains open, from the moment it is created until it is merged into the main branch. It is a critical sub-component of the overall Cycle Time.

Why It Matters ​

This metric provides a focused view of the efficiency and health of a team's code review and collaboration process.

  • Highlights Review Bottlenecks: A long Time to Merge is a clear sign of a slow or inefficient review process. It helps identify delays, whether they are due to long wait times before first review (Pickup Time) or lengthy back-and-forth discussions (Review Time).

  • Impacts Developer Flow: When PRs sit open for long periods, developers are forced to context-switch between new tasks and old PRs, which is highly inefficient and frustrating. A quick merge process allows developers to move on to the next task with confidence.

  • Indicates Collaboration Health: A smooth and fast merge process often reflects a high-trust environment with clear communication and well-understood coding standards.

How to Measure It ​

PR Time to Merge is calculated as the total time elapsed between two key events:

PR Time to Merge = Time(PR Merged) - Time(PR Created)

For deeper insights, this can be broken down:

  • Pickup Time: Time from PR creation to the first comment from a reviewer.

  • Review Time: Time from the first comment to the final approval.

Interpretation ​

  • Goal: The goal is a short and predictable Time to Merge. Many high-performing teams aim to have most PRs merged within one business day.

  • Analyze the Stages: If Time to Merge is high, break it down. Is the problem that PRs sit for days before anyone looks at them (high Pickup Time)? Or is it that the reviews themselves are long and contentious (high Review Time)?

  • Correlate with PR Size: High Time to Merge is often a direct symptom of large PR Size. Addressing PR size is frequently the first step to improving this metric.