The process capability index (Cp)combines process spread and tolerance into one index and indicates whether process variation is satisfactory.

The process capability index (Cp) is calculated by dividing the tolerance (the range of acceptable values for a product or service) by the process spread (the amount of variation in the process). A higher Cp value indicates that the process is more capable of producing products or services that meet the specified requirements. Therefore, Cp combines process spread and tolerance into one index and indicates whether process variation is satisfactory.