Engineering

Tolerance Calculator & Converter

Read a tolerance written as a ±, a limit pair or a unilateral allowance, turn it into a band in mm, µm, inches and thou, and see when it crosses into grinding.

The feature

Nominal sizeUnit on the drawingHow the tolerance is writtenThe three notations mean the same thing and are constantly misread between metric and imperial drawings.

The numbers

Plus / minus (±)e.g. 0.02

Result

0.0400 mm band

24.9800 mm to 25.0200 mm - a nominal 25.0000 mm with ±0.0200 mm equivalent.

Minimum material condition24.9800 mm

Maximum material condition25.0200 mm

Band0.0400 mm

Band (µm)40.0 µm

Band (inch)0.00157 in

Band (thou)1.57 thou

Equivalent ±±0.0200 mm

Against our published limit±0.005 mm

What this tolerance implies

This band is inside the range where the process has to be controlled rather than merely capable - a sharp tool, a finishing pass, and inspection aimed at the features that carry the tolerance.

Arithmetic on the numbers you enter, cross-checked against the machining tolerance we publish. It does not predict what any particular part will measure, and it is not an inspection result.

What you provide

Nominal size
Unit
Notation (±, limits, unilateral)
The tolerance values