How to use it
- Type the length in the Value field – thousands separators and decimals are both fine.
- Pick the unit you have under From and the unit you want under To. Swap units flips the direction.
- The headline shows the converted value and the exact factor both ways; the table below lists the same length in all thirteen units.
- Copy the result, copy the whole table, or copy the link to reopen this exact conversion.
Example
10 metres in feet: 10 × 1 m ÷ 0.3048 m/ft = 32.808399 ft (32 ft 9.7 in). The other way, 6 ft is 6 × 0.3048 = 1.8288 m, and a 26.2-mile marathon is 26.2 × 1.609344 = 42.16 km.
Formula and unit factors
Every unit is stored as its length in metres, so a conversion is one multiplication and one division:
value in TO = value in FROM × (metres per FROM) ÷ (metres per TO)
10 m → ft: 10 × 1 ÷ 0.3048 = 32.808399| Unit | Symbol | Metres |
|---|---|---|
| Nanometre | nm | 1e-9 |
| Micrometre | µm | 0.000001 |
| Millimetre | mm | 0.001 |
| Centimetre | cm | 0.01 |
| Metre | m | 1 |
| Kilometre | km | 1,000 |
| Inch | in | 0.0254 |
| Foot | ft | 0.3048 |
| Yard | yd | 0.9144 |
| Mile | mi | 1,609.344 |
| Nautical mile | nmi | 1,852 |
| Astronomical unit | AU | 149,597,870,700 |
| Light-year | ly | 9.4607304725808e+15 |
The imperial and US customary factors are exact: the 1959 international yard and pound agreement defined the yard as 0.9144 m, which fixes the inch (25.4 mm), foot (0.3048 m) and statute mile (1,609.344 m). The international nautical mile has been 1,852 m since 1929, the astronomical unit 149,597,870,700 m since IAU 2012, and the light-year is the distance light travels in a Julian year of 365.25 days at 299,792,458 m/s. US survey feet (used in some older land records, 1200/3937 m) differ from the international foot by 2 parts per million and are not included.
Sources: NIST SP 811 – Guide for the Use of the International System of Units, Appendix B (conversion factors), BIPM – The International System of Units (SI brochure), IAU 2012 Resolution B2 – re-definition of the astronomical unit.
Questions
- How many centimetres are in an inch?
- Exactly 2.54 cm. Multiply inches by 2.54 to get centimetres, or divide centimetres by 2.54 to get inches: 180 cm is 70.87 in (5 ft 10.9 in).
- How do I convert metres to feet?
- Divide by 0.3048 (or multiply by 3.2808). 10 m is 32.81 ft; 100 m is 328.08 ft. For feet and inches, keep the whole feet and multiply the remainder by 12.
- How many kilometres is a mile?
- One mile is 1.609344 km, so 5 mi is 8.05 km and 10 km is 6.21 mi. A quick mental estimate: miles × 1.6 ≈ km, km × 0.6 ≈ miles.
- What is the difference between a mile and a nautical mile?
- A statute mile is 1,609.344 m. A nautical mile is 1,852 m – originally one minute of latitude – and is used at sea and in aviation; one knot is one nautical mile per hour.