Gauge R&R Calculator

Formula

• EV = 6σ_repeatability from R̄ chart
• AV = 6σ_reproducibility from operator means
• GRR = √(EV² + AV²)
• %GRR = GRR / tolerance × 100%
• NDC = floor(1.41 × PV / GRR)

About this calculator

Part of our Fixture & Tooling Calculators collection. Clamping, locating pins, tolerance stack-up, and gauge R&R.

How it works

Enter Xbar-R study summary values from your MSA worksheet. The calculator computes repeatability (EV), reproducibility (AV), gauge R&R, part variation (PV), and total variation (TV). NDC shows how many distinct data categories your gauge can resolve.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Worked example

Default X̄-R study summary: R̄=0.012, X̄_diff=0.02, Rp=0.25, tolerance=1.

1. %GRR ≈ 9.4% of tolerance
2. Below 10% → Acceptable per common AIAG rule
3. NDC = 7 distinct categories

Result: GRR acceptable; NDC ≥ 5 is often required for process control.

When to use

• Evaluating measurement system capability from X̄-R study data
• Reporting %GRR for quality audits
• Checking NDC before using a gauge for SPC

Limitations

• Requires pre-computed R̄, X̄_diff, and Rp from your MSA worksheet
• Uses standard d2 constants; not ANOVA method
• Acceptability thresholds are rules of thumb; follow your quality standard

FAQ

What %GRR is acceptable?

Common AIAG guidance: under 10% acceptable, 10–30% marginal, over 30% unacceptable.

What is NDC?

Number of distinct categories — how many groups your gauge can reliably distinguish. NDC ≥ 5 is often required.