Use at least 30 consecutive parts from a stable process.
Cpk (what the process is doing)
Cp (what it could do if centered)
Parts outside the limits (predicted)
Mean, standard deviation, sample size

Tolerance a centered process of this spread can hold

Target CpTotal tolerance (6 x Cp x sigma)As plus or minus

Details

Cpu (upper side)
Cpl (lower side)
Parts below the lower limit (ppm)
Parts above the upper limit (ppm)
Parts inside the limits
Sigma level (3 x Cpk)
95% interval for the true mean (measured values)

Calculator by Engineer Underground · open the full page for the worked example and theory