Length Converter (m, ft, in, cm, km, mi)

Convert between metres, feet, inches, centimetres, kilometres, miles and nautical miles instantly. Type into either box and the other updates, and the exact factor used appears beneath the result so you can check it. All the arithmetic happens in your browser.

How to use it

Enter a valueType your number into either box. Conversion works in both directions, so you can start from whichever number you already have.
Choose the unitsPick from the two dropdowns, or press Swap units to reverse the conversion.
Check the factorThe line beneath the result shows the exact factor applied, for example 1 m = 3.2808399 ft.

Exact by definition

Nearly every conversion on this page is exact rather than approximate. In 1959 the United States, United Kingdom, Canada, Australia, New Zealand and South Africa agreed to define the inch as exactly 25.4 millimetres. Everything imperial follows from that one number: a foot is twelve inches, a yard is three feet, a mile is 5,280 feet.

Because those relationships are definitions, a converter has no excuse for using a rounded factor. This one stores the full value and rounds only the number it displays. Chain a few conversions together — metres to feet to inches and back — and you will land exactly where you started.

Common conversions

1 inch = 2.54 cm (exact)
1 foot = 0.3048 m (exact)
1 yard = 0.9144 m (exact)
1 mile = 1.609344 km (exact)
1 metre = 3.2808399 ft
1 nautical mile = 1,852 m (exact)

Where each unit is used

The metre is the base unit of length in the International System and is standard almost everywhere for science, engineering and trade. Feet and inches remain in general use in the United States, and survive in the UK for height, and in aviation worldwide — cruising altitudes are quoted in feet regardless of the country.

Nautical miles and knots belong to sea and air navigation, for a reason worth knowing: one nautical mile is roughly one minute of latitude, so a navigator can read distance directly off a chart's latitude scale.

Limitations

This converter handles length only. It will not convert length to area or volume — those are squared and cubed relationships, so a separate tool applies the factor the right number of times. It also assumes the international foot; if you are working with pre-2023 US land survey records, those used a very slightly different foot.

Everything runs in your browser. Nothing you enter is uploaded, and the tool keeps working if your connection drops.

Frequently asked questions

How many feet is one metre?

One metre is approximately 3.2808399 feet. The relationship is defined in the other direction: one foot is exactly 0.3048 metres, which follows from the 1959 international agreement fixing the inch at exactly 25.4 millimetres.

How many centimetres is an inch?

Exactly 2.54 centimetres. This is a definition rather than a measurement, so it carries no rounding error at all.

How many kilometres is a mile?

Exactly 1.609344 kilometres. A mile is 5,280 feet, each foot exactly 0.3048 metres, so the result is exact by definition.

What is a nautical mile and why is it different?

A nautical mile is exactly 1,852 metres, fixed by international agreement in 1929. It was originally defined as one minute of latitude along a meridian, which is what makes it useful for sea and air navigation. It is about 15% longer than a statute mile, so never substitute one for the other.

Are US and UK feet and inches the same?

Yes for all everyday purposes. Both adopted the international foot of exactly 0.3048 metres in 1959. The United States kept a separate survey foot for land surveying, larger by about two parts per million, but it was officially retired at the end of 2022.

Why does the result show fewer decimals than I expected?

Only the display is shortened, to keep everyday answers readable. The calculation runs at full double precision, so converting back and forth returns your original number.

Does this work offline?

Yes. The factors ship inside the page and the arithmetic runs on your device, so once the page has loaded no connection is needed.