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Gauge R And R Calculator

Work out gauge r and r instantly with clear inputs, formula shown and shareable results.

About Gauge R And R Calculator

Gauge repeatability and reproducibility combines equipment variation and appraiser variation in quadrature. Expressed against total study variation or against tolerance, under 10% is acceptable, 10-30% is marginal and above 30% means the measurement system cannot be trusted to make the decision it is being used for.

Formulas

Combined GRR

GRR = sqrt(repeatability^2 + reproducibility^2)

Ratios

%Study = GRR / total variation x 100; %Tolerance = 6 x GRR / tolerance x 100; ndc = 1.41 x PV / GRR

Worked example

With the default values below, Gauge R And R Calculator returns GRR As % Of Total Variation of 23.371%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Repeatability Standard Deviationminimum 0 mm
0.012 mm
Reproducibility Standard Deviationminimum 0 mm
0.008 mm
Part Variation Standard Deviationminimum 0 mm
0.06 mm
Specification Tolerance Widthminimum 0 mm
0.4 mm

Results

GRR As % Of Total Variation
23.371%
GRR As % Of Tolerance
21.633%
Combined GRR Standard Deviation
0.014422
Number Of Distinct Categories
5.87

Step by step

  1. 1Values used
  2. 2Combined GRR
  3. 3Ratios
  4. 4GRR As % Of Total Variation= 23.371
  5. 5GRR As % Of Tolerance= 21.633
  6. 6Combined GRR Standard Deviation= 0.014422
  7. 7Number Of Distinct Categories= 5.87

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Should I judge against study variation or tolerance?

Against tolerance when the gauge is used to accept or reject parts, and against study variation when it is used for process improvement and capability work. They can give very different verdicts.

What does number of distinct categories mean?

How many separate levels of part size the gauge can reliably distinguish. Fewer than five makes the gauge unusable for variables control charting.

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