Process capability

Process capability is a measurable property of a process against the specification, expressed as a process capability index (e.g., Cpk or Cpm). The output of this measurement is usually illustrated by a chronological control sample, a histogram and calculations that predict how many parts will be produced out of specification (OOS).

How to calculate cpk in excel

Two possibilitis:

  1. Excel add in with office 365
  2. Excel template with Macro

1. Excel Add in with office 365

The base of the calculation is this spreadsheet.

You can make all adjustments like:

  • inserting your logo
  • formatting cells
  • etc., etc.

To calculate adjusted values, you need the Microsoft certified „Sixsigmablackbelt Analysis“ Excel „add in“.

The free license allows the calculation of 20 values. Through mycommerce you can purchase the full license for the calculation of 200 values.

The easiest way to get the „add in“ is to install the „add in“ via Excel.

If you do not have a template yet, press the button „Create template“. If you have opened the template above, simply change the values and press the „Calculate“ button.


28 seconds to get a process capability calculation

If you already have a template customized to your needs:

  • just open it
  • put the values in
  • calculate the sheet
  • and save the results

2. Excel template with Macros

Another way is to use the similar template with macros.

process capability excel template 20150102.png
process capability excel template 20150102.png

Formula to calculate

The base for the cpk formula is described here.

cpk formula excel
cpk formula excel

For a more scientific look at process control, check out this discussion on the Minitab blog. Another option is to look at the ASQ homepage.

Please feel free to contact me, if you have any suggestions for improving this page (


[1] (MSA) Measurement System Analysis | AIAG“. (17. April 2022).

[2] „IATF 16949-2016 | AIAG“. (17. April 2022).