Gauge R&R Calculator
This Gauge R&R calculator separates measurement-system variation from part-to-part variation using a balanced crossed two-way ANOVA. Enter one row per part, operator and trial.
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- 1 Enter data
- 2 Review results
- 3 Take action
Ready for your data
Complete the inputs or load the worked example. Results will include the primary decision, interpretation and supporting metrics.
Worked example
The supplied example is a balanced 5-part, 3-operator, 2-trial study. Load it, calculate, then inspect repeatability, reproducibility, interaction and ndc rather than relying on one traffic-light label.
Load the example in the calculatorFormula and methodology
- A crossed random-effects ANOVA separates part, operator, part-by-operator and repeatability components.
- Negative estimated variance components are constrained to zero and shown through the combined result.
- Study variation is based on component standard deviations; % tolerance uses six times the Gauge R&R standard deviation.
σ²GRR = σ²repeatability + σ²operator + σ²interaction%GRR = σGRR / σtotal × 100ndc = floor(1.41 × σpart / σGRR) How to interpret the result
- Below 10% study variation is commonly considered acceptable; 10–30% may be conditionally usable; above 30% generally needs improvement.
- These bands are conventions, not universal acceptance criteria. Product risk, tolerance and measurement purpose govern the decision.
- Low ndc means the system may not distinguish enough part categories for process-control use.
Common errors and limitations
- Using an unbalanced dataset with a balanced-design formula.
- Failing to randomise measurement order or span representative part variation.
- Confusing calibration status with measurement-system capability.
Turn the calculation into an engineering decision
Share the drawing, process conditions and result context. AccuTouch can review the measurement, fixture, SPC or automation starting point.
Frequently asked questions
Gauge R&R or Gage R&R?
Both spellings refer to repeatability and reproducibility studies. “Gage” is common in AIAG material; “gauge” is widely used internationally.
Does this support nested studies?
No. This implementation is for balanced crossed studies where every operator measures every part.
What does ndc mean?
The number of distinct categories estimates how many part-to-part groups the measurement system can reliably distinguish.
Technical references
Use the current controlled standard or your organisation’s approved method where it differs from this screening tool.
Method content reviewed 13 August 2026. Independent technical approval is still required before production publication or use in a controlled quality procedure.