Length Converter
Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards, miles and nautical miles. Results update as you type. Last updated: June 2026.
Best for: Converting centimetres to inches for furniture dimensions, and switching kilometres to miles when reading running distances
Limitations: Handles standard length units and does not cover specialist engineering or typographic measures
Best suited for: Online shoppers checking whether an item fits before ordering from an overseas site
Popular Length Conversions
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Length Conversion Formulas
All metric conversions are exact by definition. The inch, foot, and yard were redefined in 1959 as exact fractions of the metre. The mile is defined as exactly 1, 609.344 metres. For a broader look at when and why to reach for each converter, see the full guide to using unit converters.
Frequently Asked Questions
How many cm in an inch?
1 inch = 2.54 centimetres exactly. This is the internationally agreed definition since 1959. To convert inches to centimetres, multiply by 2.54. To go the other way, divide by 2.54.
How do I convert feet to metres?
Multiply the number of feet by 0.3048. One foot equals exactly 0.3048 metres by definition. For example, 6 feet = 6 × 0.3048 = 1.8288 metres.
How many kilometres in a mile?
1 mile = 1.609344 km exactly. To convert miles to kilometres, multiply by 1.609344. To convert km to miles, multiply by 0.621371. A quick mental estimate: multiply km by 0.6 for a rough miles value.
What is 5 feet 11 inches in cm?
Convert each part separately: 5 feet = 5 × 30.48 = 152.4 cm. 11 inches = 11 × 2.54 = 27.94 cm. Total: 152.4 + 27.94 = 180.34 cm.
How many metres in a kilometre?
1 kilometre = 1, 000 metres. The prefix "kilo" always means 1, 000 in the metric (SI) system. Similarly, 1 kilogram = 1, 000 grams and 1 kilolitre = 1, 000 litres.
How Does the Length Converter Work?
The converter normalises your input to metres and then converts out to the unit you asked for. Metres are the natural pivot because every other length unit, metric or imperial, has an exact defined relationship to the metre. That means conversions are exact rather than approximate, and there is no accumulated error from converting through intermediate units.
The defining relationships are published in the NIST guide to SI units.
Common Length Conversions and When You Need Them
Height is the everyday case, since feet and inches are standard in the United States and the United Kingdom while centimetres are used almost everywhere else. Someone 5 feet 9 inches tall is about 175 centimetres.
Distance for travel and running is the second: a marathon is 42.195 kilometres or about 26.2 miles, and treadmills and race entries frequently mix the two. Screen and print dimensions are the third, where displays are sold by diagonal inches but layout work happens in millimetres, and manufacturing tolerances are the fourth, where a specification in thousandths of an inch has to be read against a metric drawing.
What Are the Standard Length Measurements?
The metre is an SI base unit, defined by fixing the speed of light in vacuum at exactly 299,792,458 metres per second. Imperial lengths are defined against it: the international yard is exactly 0.9144 metres, making the foot exactly 0.3048 metres and the inch exactly 25.4 millimetres. The nautical mile is defined separately as exactly 1,852 metres.