Six Sigma aims for a very low defect rate in processes and products.
Its target is about 3.4 defects per million opportunities (DPMO).
This means a process operates with nearly perfect quality and very few errors.
What is the fail rate for Six Sigma?
In Six Sigma, the commonly cited failure/defect rate is 3.4 defects per million opportunities (DPMO).
That means:
- Success rate: 99.99966%
- Failure rate: 0.00034%
- Equivalent to 3.4 failures out of 1,000,000 opportunities
The idea comes from a process operating at 6 sigma quality level, assuming a long-term process shift of 1.5 sigma.
Here’s a simple perspective:
| Sigma Level | Defects per Million | Approx. Accuracy |
|---|---|---|
| 2σ | 308,537 | 69.1% |
| 3σ | 66,807 | 93.3% |
| 4σ | 6,210 | 99.38% |
| 5σ | 233 | 99.977% |
| 6σ | 3.4 | 99.99966% |
For example:
- If a factory makes 1 million electroplated parts, Six Sigma performance would allow only about 3–4 defective parts.
- In your electroplating context, defects could be poor coating thickness, burns, pits, peeling, or missed plating areas.
A note: people sometimes say “Six Sigma means 99.9999998% perfect,” but in industry the accepted benchmark is 3.4 DPMO, not absolute perfection.
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