Is the band the plus/minus value?

No, enter the entire width between lower and upper specification limits. A ±0.10 mm drawing has a full band of 0.20 mm.

Why can an in-spec measurement miss acceptance?

The chosen guard band reserves space at both specification edges. A measurement can satisfy the drawing limits while falling outside that narrower acceptance interval.

May the nominal be negative?

Yes, a signed coordinate can have a centered tolerance band. Enter the measured coordinate using the identical datum.

Is the guard band automatically measurement uncertainty?

No, enter the band required by your agreed decision rule. Its selection may depend on uncertainty and risk assumptions that this comparison does not determine.

Quality & Metrology calculator

Bilateral Tolerance Calculator

Test a corrected measurement against a centered drawing band. Your agreed guard band narrows the acceptance interval at both specification limits.

What this calculator does

Compare a measured dimension with a symmetric tolerance band and an entered acceptance guard band.

Formula used

Specification limits = nominal ± full tolerance band ÷ 2
Acceptance limits = lower specification + guard band, upper specification − guard band
Acceptance margin = min(measured − lower acceptance, upper acceptance − measured)
Deviation = measured − nominal

Inputs explained

Nominal Dimension: Nominal or datum-relative value from the controlled drawing.
Full Tolerance Band: Full permitted drawing width before applying the acceptance guard band.
Measured Dimension: Corrected measurement result for the same dimension.
Inward Guard Band: Per-edge allowance from your agreed measurement decision rule.

How to use the result

Best suited to symmetric dimension Inspection, guard band agreement.
Asymmetric deviations require their actual upper and lower limits. This comparison does not select the uncertainty-based guard band for you.

Current U.S. benchmarks

U.S. manufacturing runs at 75.7% of capacity (Federal Reserve, Aug 2026). New factory orders are up 8.5% year over year (Census).

Common questions

Is the band the plus/minus value? No, enter the entire width between lower and upper specification limits. A ±0.10 mm drawing has a full band of 0.20 mm.
Why can an in-spec measurement miss acceptance? The chosen guard band reserves space at both specification edges. A measurement can satisfy the drawing limits while falling outside that narrower acceptance interval.
May the nominal be negative? Yes, a signed coordinate can have a centered tolerance band. Enter the measured coordinate using the identical datum.
Is the guard band automatically measurement uncertainty? No, enter the band required by your agreed decision rule. Its selection may depend on uncertainty and risk assumptions that this comparison does not determine.

Last reviewed 2026-10-06.