Tolerance defines the range of values in which a measurement is acceptable.

Before doing this section you should revise the National 4 Lifeskills Maths section on Tolerance.


A part is to be produced for a TV set. It is intended to be \(56.1mm\) long.

The part has tolerance \(56.1 + 0.4mm\)

This means that the largest acceptable size for the part is \(56.1 + 0.4 = 56.5mm\)

The smallest acceptable size for the part is \(56.1 - 0.4 = 55.7mm\)


A part for a washing machine is to be made to the length specification \(45.9 + 0.3mm\).

The constructed part is \(46.1mm\). Is it acceptable?

Largest acceptable size is \(45.9 + 0.3 = 46.2mm\)

Smallest acceptable size is \(45.9 – 0.3 = 45.6mm\)

As \(46.1\) is between these limits then the part is acceptable.