Length Converter
Convert a length or distance between millimetres, centimetres, metres, kilometres, inches, feet, yards and miles.
Result
1.609344 km
Please note: The result is an estimate and has been rounded. Actual costs and values may differ, and no rights can be derived from this calculation.
How this number is calculated
The blocks use your input. Change a value above and they update with it.
Step 1 · In metres
Step 2 · Result
How the calculation works
Convert kilometres, miles, metres, feet and more straight away. Enter a length, choose which unit to convert from and to, and see the result at once. The button swaps From and To.
Every unit of length is defined as a number of metres. A kilometre is 1,000 metres, an inch is 0.0254 metres and a mile is 1,609.344 metres. The calculator first converts your length to metres and then to the unit you choose. That way every combination of units is right, without a separate table for each pair.
The imperial units (inch, foot, yard and mile) have been defined in metres internationally since 1959, so the factors are exact. Rounding happens only at the end, to six decimal places, with halves rounded away from zero; trailing zeros are left out.
Formula
Result = length × metres per unit from ÷ metres per unit to. Metres per unit: mm 0.001, cm 0.01, m 1, km 1,000, inch 0.0254, foot 0.3048, yard 0.9144, mile 1,609.344.
Assumptions
- 1 inch is exactly 2.54 cm and 1 foot is 12 inches, exactly 30.48 cm. These are the international definitions from 1959.
- A mile is the ordinary statute mile of exactly 1,609.344 m, not a nautical mile of 1,852 m.
- Inches, feet and miles are the same length in the US and the UK.
- Rounding happens only at the end, to six decimal places: a very small length in a large unit can become 0.
Example calculations
The button fills in the calculator above, so you can carry on from there.
-
One mile
Result
1.609344 km
Length 1 · miles · kilometres
-
A marathon
Result
26.218757 mi
Length 42.195 · kilometres · miles
-
Six feet
Result
182.88 cm
Length 6 · feet · centimetres
-
American football field
Result
91.44 m
Length 100 · yards · metres
Frequently asked questions
How many cm are in an inch?
One inch is exactly 2.54 cm, as agreed internationally in 1959. So 10 inches is 25.4 cm, and 1 cm is about 0.39 inches.
How many cm are in a foot?
One foot (ft) is exactly 30.48 cm, and a foot has 12 inches. So 6 feet is 182.88 cm.
How do I convert feet and inches to cm?
Multiply the feet by 12, add the inches and multiply the total by 2.54. Someone who is 5 feet 10 inches tall, written 5′10″, is 70 inches, which is 177.8 cm.
How big is a 55-inch TV in cm?
The 55 inches is the screen diagonal, from corner to corner: 139.7 cm. On a standard widescreen (16:9) TV the picture is about 122 cm wide and 68 cm high; the TV itself is slightly larger.
How many kilometres are in a mile?
One mile is exactly 1.609344 km, and 1 km is about 0.621 miles. So 60 miles per hour is almost 97 km per hour. A nautical mile is different: it is 1,852 metres.
How many miles is a marathon?
A marathon is 42.195 km, about 26.2 miles. A half marathon is 21.0975 km, about 13.1 miles.
Sources and checks
Sources
- Weights and Measures Act 1985, Schedule 1: Definitions of units of measurement (opens in a new tab)
- NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement (opens in a new tab)
- NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically (opens in a new tab)
- Marathon | World Athletics (opens in a new tab)
How we check it
This calculator has 19 fixed checks: 16 calculations with a result that is fixed in advance, and 3 cases of invalid input that must be rejected. They all run automatically every time we publish; if one fails, the calculator does not go live.
See the calculations
- Length 1 · miles · kilometres → Result 1.609344 km
- Length 1 · inches · centimetres → Result 2.54 cm
- Length 1 · feet · metres → Result 0.3048 m
- Length 1 · feet · inches → Result 12 in
- Length 1 · metres · feet → Result 3.28084 ft
- Length 1 · kilometres · miles → Result 0.621371 mi
- Length 10 · centimetres · inches → Result 3.937008 in
- Length 42.195 · kilometres · miles → Result 26.218757 mi
- Length 6 · feet · centimetres → Result 182.88 cm
- Length 100 · yards · metres → Result 91.44 m
Changes
- : New layout: from and to with a swap button, one result and a two-step explanation. Sources added and content reviewed.
- : First version.
Last reviewed: · How we build and check our calculators
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