Understanding Defect Rejection Rate
How we calculate. Rejection % = (rejected ÷ reported) × 100. See our methodology and accuracy policy .
Real-world scenario: A typical Defect Rejection Rate case uses rejected defects 15 and total reported defects 100. Enter the same figures below to reproduce the worked path.
What is Defect Rejection Rate?
This QA/process metric measures report quality and triage efficiency. It is not a product quality score by itself.
- Includes: invalid, duplicate, cannot reproduce, works as designed (per your taxonomy)
- High rate: may mean tester training gaps or ambiguous specs
- Very low rate: can mean weak triage (accepting noise as bugs)
The Formula
Worked Example
Common Use Cases
- Triage health: monitor noise in the defect funnel
- Training: coach teams with chronic invalid reports
- Dev/QA partnership: clarify “works as designed” boundaries
Pro Tips
- Separate duplicates from invalid in deeper reports
- Do not punish filing — improve clarity of expected behavior
- Track by reporter role (manual QA vs automation vs support)
| Scenario | When to use |
|---|---|
| Percent of a number | Finding a part of a whole (tax, tip, score) |
| Percent change | Comparing old vs new values |
Limitations: Defect Rejection Rate results are estimates for learning and QA planning—not contractual SLAs. Align definitions with your org’s quality glossary before executive reporting.
Common mistakes
- Swapping part and whole: The denominator must be the full total, not a subset.
- Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
- Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.
When to use this calculator
- Use this page when your wording matches defect rejection rate and the form labels on screen.
- Use percent of a number for “what is X% of Y?” problems.
- Use number is what percent when you know part and whole and need the percent.
Still unsure about defect rejection rate? Start with the quick answer above, then open the linked calculator that matches your wording.
❓ Frequently Asked Questions
How do I use this defect rejection rate calculator?
For defect rejection rate (percentage calculator), enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.
What formula does this page use?
See the quick answer and formula box above for defect rejection rate—the same percentage calculator expression is applied to your inputs.
What if my result looks wrong?
When checking defect rejection rate, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.
Authoritative References
For software quality metrics definitions, consult established engineering sources:
- ISTQB — software testing glossary and practices
- ISO/IEC 25010 — systems and software quality models
- IEEE — software engineering standards