How to convert length units
Every length unit here is defined exactly in metres. The inch has been exactly 2.54 cm since the 1959 international yard and pound agreement, so a foot (12 inches) is 0.3048 m, a yard (3 feet) is 0.9144 m and a mile (1,760 yards) is 1,609.344 m. To convert, the converter changes your value to metres and then to the unit you want, so every result uses exact factors.
- Centimetres to inches: divide by 2.54 (30 cm = 11.81 in).
- Feet to metres: multiply by 0.3048 (6 ft = 1.8288 m).
- Kilometres to miles: divide by 1.609344 (10 km = 6.2137 mi).
- Height in feet and inches: 5 ft 7 in = 67 in × 2.54 = 170.18 cm.
Common length conversion factors
| Unit | Equals | Reverse |
|---|---|---|
| 1 centimetre | 0.3937007874 in | 1 inch = 2.54 cm |
| 1 foot | 0.3048 m | 1 metre = 3.280839895 ft |
| 1 kilometre | 0.6213711922 mi | 1 mile = 1.609344 km |
| 1 millimetre | 0.0393700787 in | 1 inch = 25.4 mm |
| 1 foot | 30.48 cm | 1 centimetre = 0.032808399 ft |
| 1 yard | 0.9144 m | 1 metre = 1.093613298 yd |
| 1 nautical mile | 1.852 km | 1 kilometre = 0.5399568035 nmi |
| 1 light-year | 94,60,73,04,73,000 km | 1 kilometre = 1.0570008 × 10⁻¹³ ly |
Length conversions
Each of these has its own page with the formula, worked examples and a full conversion table:
All length units on this converter
| Unit | Symbol | 1 unit equals | System |
|---|---|---|---|
| Nanometre | nm | 1 × 10⁻⁹ m | Metric |
| Micrometre | µm | 0.000001 m | Metric |
| Millimetre | mm | 0.001 m | Metric |
| Centimetre | cm | 0.01 m | Metric |
| Decimetre | dm | 0.1 m | Metric |
| Metre | m | 1 m | Metric |
| Kilometre | km | 1,000 m | Metric |
| Inch | in | 0.0254 m | Imperial / US |
| Foot | ft | 0.3048 m | Imperial / US |
| Yard | yd | 0.9144 m | Imperial / US |
| Mile | mi | 1,609.344 m | Imperial / US |
| Mil (thou) | mil | 0.0000254 m | Imperial / US |
| Hand | hh | 0.1016 m | Imperial / US |
| Fathom | ftm | 1.8288 m | Imperial / US |
| Chain | ch | 20.1168 m | Imperial / US |
| Furlong | fur | 201.168 m | Imperial / US |
| Nautical mile | nmi | 1,852 m | Navigation |
| Ångström | Å | 1 × 10⁻¹⁰ m | Science |
| Astronomical unit | au | 1,49,59,78,70,700 m | Science |
| Light-year | ly | 9.4607305 × 10¹⁵ m | Science |
| Parsec | pc | 3.0856776 × 10¹⁶ m | Science |
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54 centimetres. To convert inches to cm, multiply by 2.54; to convert cm to inches, divide by 2.54.
How many feet are in a metre?
1 metre is about 3.28084 feet, or 3 feet 3.37 inches. 1 foot is exactly 0.3048 metres.
What is the difference between a mile and a nautical mile?
A (statute) mile is 1,609.344 m, used on roads. A nautical mile is 1,852 m, based on one minute of latitude, and is used at sea and in aviation.
How far is a light-year?
The distance light travels in a Julian year: 9,460,730,472,580.8 km, about 9.46 trillion kilometres.