# 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.

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