ClarityKitFind a tool
Statistics

Process Capability Cp Cpk Calculator

Estimate capability indices from specification limits, process mean and within-process standard deviation.

Data stays on this deviceConvention explained below
Process quality desk
Process quality desk

Main result is Cpk. Review process stability and sigma estimation before interpreting.

See the method

Set specifications and variation

Runs on your device

Capability indices

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter lower specification limit, upper specification limit, process mean, within-process standard deviation.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Cp=(USL−LSL)/(6σ); Cpk=min[(USL−mean)/(3σ),(mean−LSL)/(3σ)].

A WORKED EXAMPLE

Using lower specification limit = 9, upper specification limit = 11, process mean = 10, within-process standard deviation = 0.2, the result is 1.66666667. Change these example inputs to match your task; use the method above to check each step.

Understanding your result

Main result is Cpk. Meaningful capability analysis requires a stable process, appropriate distribution and a defensible within-process sigma estimate.

What to keep in mind

Main result is Cpk. Meaningful capability analysis requires a stable process, appropriate distribution and a defensible within-process sigma estimate. A descriptive or probability calculation under the stated assumptions. Check the sample design and model before interpreting results.

Common questions

How do I use this process capability cp cpk calculator?

Estimate capability indices from specification limits, process mean and within-process standard deviation. Enter lower specification limit, upper specification limit, process mean, within-process standard deviation. The starting example is editable; use values for the same system or project.

Which assumptions affect this result?

Main result is Cpk. Meaningful capability analysis requires a stable process, appropriate distribution and a defensible within-process sigma estimate.

Methodology maintained by ClarityKit. How these tools are built and checked.