Cp & Cpk Calculator
Calculate process capability in seconds and see which specification side is limiting your Cpk.
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Calculated from the values above.
Who it is for
Quality engineers, manufacturing teams and anyone who needs a quick capability check from known summary statistics.
What you get
Cp, Cpk, upper and lower capability indices, plus a concise interpretation of the limiting side.
Interpreting Cp and Cpk
Use specification limits, process mean and a meaningful standard deviation estimate from an appropriate process study.
- Enter the lower and upper specification limits, mean and positive standard deviation.
- Compare Cp (potential width relative to specification) with Cpk (capability after considering centring).
- Review Cpu and Cpl to understand which specification side limits the Cpk result.
Process stability and the method used to estimate σ matter. Do not use a calculated value alone as evidence of conformity with a customer's capability requirement.
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