Number of inspection points / characteristics per unit
Defects across all units inspected
DPMO
Defects per Million Opportunities
SIGMA LEVEL
With 1.5σ shift
Yield (RTY)
Process yield %
DPU
Defects per unit
DPMO = (Defects / (Units × Opps)) × 1,000,000
Yield = (1 − Defects/(Units×Opps)) × 100%
σ = NORMSINV(1 − DPMO/1,000,000) + 1.5

Sigma level reference (with 1.5σ shift)

Sigma LevelDPMOYieldCpkQuality classification
3.499.99966%2.0World class — aerospace, medical implants
23399.977%1.67Excellent — top automotive, surgical devices
6,21099.38%1.33Good — typical IATF 16949 supplier
3.5σ22,75097.7%1.17Acceptable
66,81093.32%1.0Industry average — most Indian SMEs
2.5σ158,65584.13%0.83Below average
308,53869.15%0.67Poor — cannot meet customer expectations
691,46230.85%0.33Critical — process not in control