Length Converter
Converters · Added 9 August 2026
Convert any length between metric and imperial units, from millimetres to nautical miles, using the exact internationally agreed factors.
Result
1 cm in inch
0.393700787 in
1 cm = 0.393700787 in
The same value in every unit
- Millimetre (mm)
- 10
- Centimetre (cm)
- 1
- Metre (m)
- 0.01
- Kilometre (km)
- 0.00001
- Inch (in)
- 0.393700787
- Foot (ft)
- 0.032808399
- Yard (yd)
- 0.010936133
- Mile (mi)
- 0.00000621371192
- Nautical mile (nmi)
- 0.00000539956803
- Micrometre (µm)
- 10,000
All factors are exact by definition: one inch is precisely 0.0254 metres, and the mile, yard and foot follow from it.
How to use the length converter
- 1Type the number you want to convert into the Value box. Thousands separators and spaces are ignored, so pasting 1,760 works fine.
- 2Pick the unit you are converting from, then the unit you want. Metric and imperial units are grouped separately in each dropdown.
- 3Read the answer in the result panel. Underneath it, the same measurement is listed in every other unit at once — often faster than converting twice.
- 4Use Swap units to reverse the direction without retyping, or Copy result to put the conversion on your clipboard.
Examples
Height in centimetres to feet and inches
- Input
- 180 centimetres
- Result
- 70.8661417 inches (5 ft 10.9 in)
Take the whole feet from the inches figure and divide the remainder: 70.87 in is 5 feet with 10.87 inches left over.
A running distance
- Input
- 5 kilometres
- Result
- 3.10685596 miles
The familiar 5K, 10K and half marathon distances are 3.11, 6.21 and 13.11 miles.
Screen size to millimetres
- Input
- 27 inches
- Result
- 685.8 millimetres
About the length converter
Metric and imperial, and why both survive
Almost every country measures length in metres, but imperial units persist in specific niches that resist change. Screens and pipes are sized in inches worldwide. Aviation reports altitude in feet regardless of the country. Property in the United States, and often in India and the UK, is advertised in square feet even where the rest of the paperwork is metric.
The result is that most people need both systems occasionally rather than one system constantly, which is exactly when a conversion is easy to get wrong — you do it rarely enough that the factor is not in your head.
The factors are exact, not approximate
It is worth knowing that imperial units are now defined in terms of metric ones. The international yard and pound agreement of 1959 fixed the yard at exactly 0.9144 metres, which makes the foot exactly 0.3048 m and the inch exactly 0.0254 m.
This means a conversion between inches and centimetres has a right answer with no rounding built into the factor itself. Any imprecision you see comes from displaying a finite number of digits, not from the conversion.
Common places a length conversion goes wrong
The most frequent error is mixing up a length conversion with an area or volume one. A room 10 feet across is 3.048 metres across, but a room of 100 square feet is 9.29 square metres, not 30.48 — because area factors are squared. If you are converting a floor plan rather than a distance, use the area converter instead.
The second is the feet-and-inches format. A height of 5.9 feet is not 5 feet 9 inches; it is 5 feet 10.8 inches, because the fractional part is tenths of a foot rather than inches. Converting to plain inches first, as the result panel does, avoids the trap entirely.