Workshop calculators
Measurement converter
Convert between inches, feet, millimetres, centimetres and metres exactly, with the nearest 1/16 in and feet-and-inches.
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Worked example
23/32 in =
18.25625 mm
Exact
- Feet
- ≈ 0.0599 ft
- Millimetres
- 18.25625 mm
- Centimetres
- 1.825625 cm
- Metres
- 0.01825625 m
How it works
An inch is defined as exactly 25.4 mm, so every conversion is worked out as an exact fraction. A foot is 12 in, a centimetre 10 mm and a metre 1000 mm. Rounding happens only when the answer is displayed.
Any inch measurement you can read on a tape, down to 1/64 in, converts to an exact millimetre value, shown in full. Other fractions, such as 1/3 in, don’t end as decimals, so they are rounded to 6 decimal places of a millimetre and marked “≈”. Metric to inches is shown exactly when the result is a whole number of 64ths; otherwise it is given to the nearest 1/16 in, as you would read it on a tape, and marked “≈”. The result card always says which rounding was used.
Example: 23/32 in is exactly 18.25625 mm (23 × 25.4 ÷ 32), shown in full.