Convert between inch fractions, decimal inches and millimetres, with the nearest fraction to any decimal or metric value.
Tape measures and rulers in inches are marked in fractions, not decimals. This tool converts a decimal or metric measurement to the nearest usable fraction, and shows the exact decimal and millimetre values too.
Rounding to a fraction introduces a tiny error. For precise engineering work, use the decimal or millimetre value rather than the rounded fraction.
Multiply the decimal part by the denominator (such as 16), round to the nearest whole number, then simplify. The calculator does this and simplifies the fraction for you.
Exactly 25.4mm. To convert inches to millimetres multiply by 25.4, and to go the other way divide by 25.4.
Exactly one half (1/2) inch, which is also 12.7mm. The calculator shows the nearest fraction along with the exact decimal and mm values.
Use 1/16in for general woodworking and DIY, and 1/32in or 1/64in for fine joinery and engineering where more precision is needed.
It is the nearest fraction for the denominator you choose, so there can be a tiny rounding difference. The decimal and mm values shown are exact.
