# How is Cp and Cpk calculated?

Unlike Cp, Cpk makes no assumption that the process mean is centered between the specification limits. The formula for the calculation of Cpk is Cpk = min(USL – μ, μ – LSL) / (3σ) where USL and LSL are the upper and lower specification limits, respectively.Click to see full answer. Moreover, what is the formula for CP and CPK? Calculating Cpk using a Z Value If you have a Z value, the equation is very easy; Cpk can be determined by dividing the Z score by three. A z score is the same as a standard score; the number of standard deviations above the mean. Z = x – mean of the population / standard deviation. what is CP CPK value? Cp and Cpk. Cp and Cpk, commonly referred to as process capability indices, are used to define the ability of a process to produce a product that meets requirements. In other words, they define what is expected from an item for it to be usable. Similarly, you may ask, what does a Cpk of 1.33 mean? Process capability index (Cpk) is a statistical tool, to measure the ability of a process to produce output within customer’s specification limits. Cpk = or >1.33 indicates that the process is capable and meets specification limits.What is difference between CP & CPK?Cp is the simplest indicator of a process capability while Cpk gives a better picture. 2. Cp is also known as the “process potential index” while Cpk is known as “process capability index” or “process performance index”.