Process Capability Index Calculator


Instructions: You can use this Process Capability Index Calculator, by providing the lower specification limit, the upper specification limit, and the mean \((\bar X)\) and standard deviation (\(\sigma\)) of the process, using the form below:

Lower Specification =
Upper Specification =
Process Mean \(\bar X\) =
Process Standard Deviation \(\sigma\) =

Process Capability Index Calculator

More about the Process Capability Index Calculator for you to have a better understanding of the results provided by this solver. The capability index of a process is a measure of the percentage of non-conforming elements produced by a process, when the process is not centered. The higher the capability ratio is, the lower the percentage of non-conforming produced by the process. The capability index is computed by using the following formula:

\[ C_{pk} = \displaystyle \min\left( \frac{\text{Upper Specification}-\text{Mean}}{3\sigma} , \frac{\text{Mean} - \text{Lower Specification} }{3\sigma} \right) \]

Notice that this capability ratio formula is used for the case that the process is not centered. When the process is centered, you should use a process capability ratio instead.




In case you have any suggestion, or if you would like to report a broken solver/calculator, please do not hesitate to contact us.

log in

reset password

Back to
log in