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Length converter: feet, inches, mm, cm and metres
One foot is exactly 0.3048 metres: 30.48 cm, 304.8 mm or 12 inches. One inch is exactly 25.4 mm. Type any length below, in any unit, with fractions like 3 1/2 or feet and inches like 5′ 6″, and see it in every unit at once, with inches as the nearest 1/8, 1/16 or 1/32.
The exact definitions
Imperial and metric lengths are tied together by definition, so these conversions are exact: one inch is 2.54 centimetres, one foot is 0.3048 metres, and one yard is three feet (NIST). That’s why 1 foot is exactly 304.8 mm and 1 inch exactly 25.4 mm, with nothing rounded. The U.S. survey foot, a slightly different foot once used for land surveying, has been retired in favour of this one (NIST).
Common conversions
| From | To | Multiply by |
|---|---|---|
| inches | millimetres | 25.4 |
| inches | centimetres | 2.54 |
| feet | metres | 0.3048 |
| feet | centimetres | 30.48 |
| yards | metres | 0.9144 |
| millimetres | inches | ÷ 25.4 |
| metres | feet | ÷ 0.3048 |
Fractions of an inch in millimetres
Each sixteenth of an inch is exactly 1.5875 mm (25.4 ÷ 16).
| Inch | mm | Inch | mm |
|---|---|---|---|
| 1/16″ | 1.5875 | 9/16″ | 14.2875 |
| 1/8″ | 3.175 | 5/8″ | 15.875 |
| 3/16″ | 4.7625 | 11/16″ | 17.4625 |
| 1/4″ | 6.35 | 3/4″ | 19.05 |
| 5/16″ | 7.9375 | 13/16″ | 20.6375 |
| 3/8″ | 9.525 | 7/8″ | 22.225 |
| 7/16″ | 11.1125 | 15/16″ | 23.8125 |
| 1/2″ | 12.7 | 1″ | 25.4 |
About rounding
The decimal results are exact to the four decimal places shown. The fraction results round to the nearest 1/8, 1/16 or 1/32 of an inch, whichever you pick, and show ≈ when they had to round. If a measurement has to be precise, choose a finer fraction, or work in millimetres.
Questions
How many centimetres are in a foot?
Exactly 30.48. A foot is defined as 0.3048 metres (NIST), which is 30.48 cm or 304.8 mm.
How do I convert inches to millimetres?
Multiply by 25.4. An inch is exactly 2.54 cm (NIST), so 3 inches is 76.2 mm.
What is 5/8 of an inch in mm?
15.875 mm exactly: 5 ÷ 8 × 25.4. The table on this page lists every sixteenth of an inch.
How do I convert metres to feet and inches?
Divide by 0.3048 to get feet, then multiply the decimal part by 12 for inches. 2.5 m is 8.2021 ft, which is about 8′ 2 7/16″. The converter does it for you.
Can I type feet and inches together?
Yes. Type it like 5' 6" or 5' 6 1/2" and the converter reads it as feet and inches, whatever unit is selected.