Bug Closure Rate
Bug Closure Rate measures the number of bugs resolved during a given time period. It reflects how consistently the team addresses incoming defects and whether the bug backlog is growing or shrinking.
Calculation
A bug is considered “closed” when its associated ticket is marked as resolved, done, or completed in the issue tracker. This metric is calculated using a fixed time window, typically one week or sprint.
The metric is calculated as:
bug closure rate = number of bugs closed ÷ time period
Goals
Bug Closure Rate helps teams monitor their ability to resolve reported issues. It answers questions like:
- Are we keeping pace with bug reports?
- Is our backlog of open issues increasing or shrinking?
- Are specific systems or teams falling behind on defect remediation?
This metric supports long-term product health by ensuring defect inflow doesn’t outpace resolution capacity.
Variations
Bug Closure Rate may also be referred to as Defect Resolution Rate or Bug Outflow Rate. Common breakdowns include:
- By severity, such as P1 vs. P3 bugs
- By age, highlighting how long bugs were open before closure
- By team or service, to identify backlogs by ownership
- By sprint or release, to monitor stability across delivery cycles
- By source, such as QA vs. user-reported bugs
Some teams compare closure rate directly against Defect Rate to evaluate whether they’re resolving issues faster than they’re being created.
Limitations
Bug Closure Rate measures volume, not impact. Closing ten cosmetic bugs is not equivalent to resolving one production outage.
The metric also depends on consistent ticket hygiene. Without proper closure practices or severity tagging, the data may not reflect true resolution progress.
To make closure rates more meaningful, combine them with:
| Complementary Metric | Why It’s Relevant |
|---|---|
| Average Bug Backlog Size | Shows whether closure rate is keeping backlog growth under control |
| Time Spent on Bugs | Reveals how much effort is required to close bugs, and whether it’s sustainable |
| Stale Defect Percentage | Highlights whether closure is timely or delayed |
Optimization
Improving Bug Closure Rate involves consistent triage, prioritization, and balancing bug fixes with roadmap work.
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Allocate consistent capacity for bugs. Don’t defer all defect work to later sprints, schedule time intentionally
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Triage and tag bugs quickly. Ensure incoming issues are reviewed and prioritized early
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Use SLAs for high-severity bugs. Resolve P0–P1 issues within defined windows to minimize user impact
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Automate low-complexity fixes. Use tooling or templates to accelerate resolution of simple or repeatable bugs
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Track resolution blockers. Identify root causes of slow closures, whether technical, process-related, or organizational
Bug closure rate is a measure of follow-through. When resolution matches or exceeds inflow, quality stabilizes, and teams stay focused on the future, not the past.
