Free quality statistics tool
Defect Rate, PPM & Yield Calculator
Convert observed production defects into PPM, yield and annual quality exposure. Use actual inspection results—not capability-model estimates.
Free · No registration · No installation
Observed production result
Your observed result
Enter inspection counts and annual volume, then calculate to see observed PPM, yield and annual defective units.
Count-based only. No normality assumption. No Cp, Cpk, Pp or Ppk calculation.
What this calculator measures
Observed performance is defective units divided by inspected units. Multiply this proportion by 100 for defect rate, or by 1,000,000 for PPM. Yield is the proportion of inspected units that are not defective.
Annual defective units equal the unrounded observed proportion × annual volume. Optional direct scrap exposure equals annual defective units × USD cost per defective unit. Annual volume never changes the observed rate, PPM or yield.
Observed PPM vs predicted PPM
Observed PPM comes from actual inspection counts. Predicted PPM comes from a statistical model and requires assumptions. Never treat the two as interchangeable or use observed PPM to prove capability.
The Cpk to PPM conversion guide and PPM to Cpk conversion guide explain model-based relationships—not a capability inference from these counts.
When to use this calculator
- Production inspection summary for a defined period.
- Supplier scorecard with consistent inspection coverage.
- Monthly scrap review using a representative direct unit loss.
- Containment effectiveness review with comparable defect definitions.
What this calculator cannot prove
Counts alone do not prove Cp/Cpk/Pp/Ppk, process stability, normality, measurement-system adequacy, root cause or customer acceptance. Sampling may miss defects, and zero observed defects is not a guarantee.
Explore the Quality Statistics Knowledge Center or use the Process Capability & Performance Calculator to examine measured process behavior.
Frequently asked questions
How do I calculate PPM from defects?
Divide defective units by inspected units and multiply by 1,000,000. For example, 10 defective units from 10,000 inspected units equals 1,000 observed PPM. Count defective units, not individual defects: a unit with several defects is counted once.
What is the difference between defect rate and PPM?
They express the same observed proportion on different scales. Defect rate uses a percentage; PPM uses parts per million. A defect rate of 0.1% equals 1,000 PPM.
Is observed PPM the same as Cpk-based PPM?
No. Observed PPM uses actual inspection counts. Cpk-based PPM is a model-based estimate that depends on distribution, centering and other assumptions. They are not interchangeable.
Can I use this calculator for supplier performance?
Yes, as an inspection-based input to a supplier scorecard. Keep the production period, inspection coverage, sampling approach and defect definition consistent. It does not establish customer acceptance.
Does a low defect rate prove my process is capable?
No. Counts alone do not establish capability, process stability or measurement-system adequacy. Zero observed defects also does not guarantee zero defects in the wider production population.