Length Converter
Length is the unit people convert most often, usually because two measurement systems are in play: metric (metres, centimetres, kilometres) in most of the world and imperial or US customary (inches, feet, yards, miles) in the United States and, for road signs and everyday height, the United Kingdom. This converter handles both in one place and gives the exact factor so you can see how the answer was reached. Use it for recipes’ pan sizes, furniture, travel distances, running routes and DIY.
How to use the length converter
- Enter the value you want to convert.
- Choose the unit it is in (From) and the unit you want (To).
- Read the answer, the conversion factor and the quick conversions into other length units below it.
Formula
Every length is converted through the metre. Result = value × (metres per “from” unit) ÷ (metres per “to” unit). The international definitions are exact: 1 inch = 2.54 cm, 1 foot = 0.3048 m, 1 yard = 0.9144 m and 1 mile = 1,609.344 m.
Worked examples
A marathon in kilometres
A marathon is 26.2 miles, which is 42.1648 km.
Height in centimetres
A person who is 5 ft 10 in tall is 70 inches, or 177.8 cm.
A short route in feet
500 metres is 1,640.42 feet, or 546.807 yards.
Common length conversions
| Conversion | Result |
|---|---|
| 1 in | 2.54 cm |
| 1 ft | 0.3048 m |
| 1 yd | 0.9144 m |
| 1 mi | 1.60934 km |
| 100 m | 328.084 ft |
| 5 km | 3.10686 mi |
| 10 cm | 3.93701 in |
A short history of the foot and the metre
The metre was defined in revolutionary France in the 1790s as one ten-millionth of the distance from the pole to the equator, and is today fixed by the speed of light. The international inch of exactly 2.54 cm was agreed by the US, UK and other Commonwealth nations in 1959, ending small differences between national inches. For other systems see the unit converter hub.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- Convert 5 feet 11 inches (71 in) to centimetres.
Show answer
71 in in cm: 180.34
- How many miles is a 10 km run?
Show answer
10 km in mi: 6.213711922
Common mistakes to avoid
- Confusing the statute mile (1,609.344 m) with the nautical mile (1,852 m), which is used at sea and in aviation.
- Rounding the 2.54 inch factor. It is exact by definition, so there is no need to use 2.5 or 2.54000001.
- Forgetting that feet-and-inches heights must be turned into total inches first (5 ft 10 in = 70 in).
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54 centimetres, a value fixed by the 1959 international yard and pound agreement.
How many feet are in a mile?
A statute mile is 5,280 feet, which is 1,609.344 metres.
How do I convert feet to metres?
Multiply by 0.3048. For example, 10 ft × 0.3048 = 3.048 m.
Is a US mile the same as a UK mile?
For everyday use, yes — both are 1,609.344 metres. The older US survey mile differed by about two parts per million and is being retired.
Why do some countries still use miles?
The US and a few other places never completed metrication; the UK uses miles on road signs while using metric for most other measurements.
Sources and further reading
Reviewed September 26, 2026 by the SolveCalcPro editorial team. Found a mistake? Tell us; see our editorial policy.