Free improvement tool
Process capability calculator: Cp, Cpk, Pp and Ppk
Paste your measurements in time order, then enter the lower and/or upper specification limit. Everything runs in your browser; nothing is uploaded.
Cp, Cpk, Pp and Ppk in plain words
- Cp compares the width of the limits with the spread of the process.
- Cpk also checks how centred the process is. It uses the nearer limit.
- Within results use the short-term spread from the moving range (MR̄ ÷ 1.128). Overall results (Pp, Ppk) use the standard deviation of all the data.
- A common target is Cpk of 1.33 or more.
