Two-sided process capability indices
Separate specification width from off-center operation using Cp and Cpk.
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Enter ordered specification limits and a strictly positive representative process standard deviation. Use the same measurement units for all four inputs.
The starting values are hypothetical. Results update as you edit. Use aggregate or synthetic inputs only.
Calculation results
- Cp
- 1.6666667
- Cpk
- 0.66666667
- Upper-side index
- 0.66666667
- Lower-side index
- 2.6666667
How to interpret the output
Assumes a stable process and an appropriate dispersion estimate. Gives point estimates only. Distributional evidence is needed for tail probabilities. Specification limits must come from an external requirement. Method checked 9 November 2026.
Method reference