Length Converter

Convert a length or distance between millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and nautical miles, with all equivalents shown at once.

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Length & Distance

Convert length and distance between metric and imperial units

Enter a value and choose a unit to see all equivalents at once — millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and nautical miles.

Value From unit

Metric

Millimetres 1,000 mm

Centimetres 100 cm

Metres 1 m

Kilometres 0.001 km

Imperial

Inches 39.3701 in

Feet 3.28084 ft

Yards 1.09361 yd

Miles 0.000621 mi

Nautical

Nautical miles 0.00054 nmi

Quick reference

1 inch = 2.54 cm
1 foot = 30.48 cm
1 yard = 0.9144 m
1 mile = 1.609344 km
1 nmi = 1.852 km

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Length & Distance

Length unit conversion: metres, feet, miles, and all the in-between explained

A length converter lets you switch any distance or dimension between metric and imperial units instantly. This online length converter handles millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and nautical miles in one place, showing all equivalents at once so you can pick whichever unit fits your task.

Metric and imperial length units compared

The metric system builds every length unit around powers of ten. One centimetre is one hundredth of a metre; one kilometre is one thousand metres. That makes arithmetic straightforward: moving between metric units is just multiplication or division by 10, 100, or 1,000. The imperial system works differently, using historically defined units that share no consistent ratio — 12 inches in a foot, 3 feet in a yard, 1,760 yards in a mile — which is precisely why a converter is so useful.

In practice, most countries use metric for almost everything, while the United States continues to use imperial for everyday distances (miles, feet, inches) and a handful of other countries use imperial for particular contexts such as aviation altitude in feet or body height in feet and inches. A free online length converter bridges those two systems without any mental arithmetic.

The exact conversion factors used by this converter

Every conversion in this tool is derived from a single base unit: the metre. The tool converts the input into metres first and then divides by the target unit factor to reach the final value. All factors here are exact definitions rather than approximations, as set out in international measurement standards.

One inch is defined as exactly 2.54 centimetres — a definition that has been internationally agreed since 1959. Every other imperial unit follows from that: one foot is 12 inches, giving exactly 0.3048 metres; one yard is 3 feet, giving 0.9144 metres; one international mile is 1,760 yards, giving 1,609.344 metres exactly.

1 inch = 2.54 cm (exact)

The internationally defined relationship between the inch and the centimetre, agreed in 1959.

1 foot = 12 inches = 0.3048 m (exact)

The exact metric equivalent of one foot, derived from the inch definition.

1 mile = 1,760 yards = 1,609.344 m (exact)

The exact metric equivalent of one international mile.

1 nautical mile = 1,852 m (exact)

The international nautical mile, used in aviation and marine navigation.

When each unit is most useful

Millimetres are used in precision manufacturing, engineering drawings, small-scale craft, and medical contexts where fine measurement matters. Centimetres appear in everyday measurement tasks in metric countries — clothing sizes, room dimensions, human height. Metres cover most everyday distances from the length of a room to the height of a building. Kilometres handle longer distances: road distances, city separations, marathon race lengths.

Inches remain the dominant unit in the United States and Canada for construction, screen sizes, tyre widths, and body height. Feet are used for building dimensions, ceiling heights, and altitude in aviation. Yards survive mainly in American football, golf, and fabric measurement. Miles are the standard road-distance unit in the UK and the United States. Nautical miles are the standard for marine and aviation distance, equal to one minute of latitude on the Earth's surface.

Screen sizes are measured diagonally in inches across most of the world.
Aviation altitude is almost universally reported in feet regardless of metric adoption.
GPS coordinates use decimal degrees, but route distances use km or miles by region.
Running races (5K, 10K, half-marathon, marathon) use metric even in the United States.

Using this length converter for common tasks

To convert centimetres to inches, enter the value in centimetres and choose centimetres as the source unit — the equivalent in inches appears automatically. The converter is useful for any everyday unit switch: checking whether a product listed in inches will fit a space measured in centimetres, converting a road distance from miles to kilometres before a trip, or understanding a height given in feet and inches as a centimetre measurement.

For tasks that require very high precision such as engineering tolerances, use the scientific-notation output this converter provides for very small or very large values. For everyday tasks like room planning, the regular decimal output is precise enough.

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