Quality & Metrology worked example
Process Capability Cp with tolerance width of 0.75 spec units: a worked example
This scenario runs the process capability cp calculation on the strong side: tolerance width of 0.75 spec units, with every other input held at its documented default. Use it when you need a quick Cp on a characteristic and want to see how much of the tolerance the process is consuming.
The inputs for this scenario
- Tolerance width (USL minus LSL): 0.75 spec units (raised for this scenario; the documented default is 0.3)
- Process spread (6 sigma): 0.24 spec units (unchanged)
- Reporting conversion factor: 1 x (unchanged)
Working through the calculation
- Applying the documented formula (Cp = tolerance width รท process spread) to the inputs above produces each figure below.
- At this operating point the engine returns 3.13 Cp for process capability cp, the number this scenario is built around.
- At this operating point the engine returns 3.13 value for raw ratio.
- At this operating point the engine returns 1 x for conversion factor.
- At this operating point the engine returns 0.24 value for process spread (6 sigma).
How this compares with the baseline
- Against the tool's baseline example, where tolerance width sits at 0.3 spec units and the headline result is 1.25 Cp, this scenario comes in 150% above the baseline at 3.13 Cp.
- Use it during capability studies and process validation to judge whether process variation is tight enough for the specification, before worrying about centering. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.
Results at a glance
- Process capability Cp: 3.13 Cp (headline result)
- Raw ratio: 3.13 value
- Conversion factor: 1 x
- Process spread (6 sigma): 0.24 value
Run it with your numbers
- Every input above is editable in the live Process Capability Cp calculator, which recalculates instantly and can be shared with the inputs intact.
Last reviewed 2026-05-12.