Cp Cpk Template for Excel

You Don't Have to be a Statistician to Analyze Capability using Cp and Cpk

What's Cool about the QI Macros Cp Cpk Template for Excel?

Just enter your target value, tolerances and measurements in the yellow shaded areas. The worksheet will automatically calculate Cp, Cpk, Pp, and Ppk. It has space for up to eight characteristics and 100 measurements:

Here is an Example of the QI Macros Cp Cpk Template

One Sided Spec Limits
If you need to perform a one tailed capability analysis, just delete the formula in either the USL or LSL field.

Cp and Cpk Calculation Mistakes to Avoid

Most people try to calculate Cp as the upper spec limit minus the lower spec limit divided by six times the standard deviation:

Cp = (USL-LSL)/6*Stdev
However, this is actually the formula for process performance (Pp).

The QI Macros Cp Cpk template uses the correct formula which estimates the standard deviation from the average of the ranges divided by a constant (Rbar/d2).

Cp = (USL-LSL)/6*Rbar/d2
The same is true for Cpk.

Process Capability Analysis Quick Reference Card

To open the template from the QI Macros menu, select SPC Charts, then Cp Cpk Worksheet about 2/3 down the list

Cp Cpk Template On QI Macros Menu

To expand the template, follow these instructions (Click Here).

See how it works! Add or paste data in yellow cells below...

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