Quality Quick Calculator: Common Quality Formulas in One Click
What is the Quality Quick Calculator?
It concentrates the conversion relationships used daily in quality management into one tool: Cpk to yield (under normality), Cpk to ppm, tolerance/standard-deviation/capability relations, sampling-size estimation from confidence and error, and percent to ppm/DPMO conversion. Centralizing the common formulas keeps the definitions consistent, avoids manual table lookups and arithmetic errors, and makes shop-floor decisions faster; every module shows its formula for checking.
When to Use It
Use it for quick capability and defect-rate estimates in review meetings, rough sample-size calculations before writing an inspection plan, spec-versus-capability conversions, and everyday cross-checks of quality figures. It is also handy when explaining indicators such as ppm to customers, because the conversion relationships are shown with their assumptions.
How to Use It (Step by Step)
Pick a module, enter the known values (for example Cpk, or the specification and standard deviation, or confidence and allowable error for sampling), and read the result with its formula note and assumption hints (normal distribution, one- or two-sided). For decisions that matter, re-verify with the dedicated professional tools — the quick calculator is for fast judgment, not for formal submissions.
Key Formulas / Example
Under normality with two-sided specifications, Cpk = 1.33 corresponds to about 63 ppm, and about 66 ppm under the common 1.5σ-shift long-term convention — the data behind the 1.33-is-enough rule of thumb. Conversions: 1% = 10,000 ppm and 0.001% = 10 ppm; the tool converts both ways.