Length Converter

This converts between any pair of metres, centimetres, millimetres, kilometres, inches, feet, yards, miles and nautical miles. It replaced the separate metres-to-feet, inches-to-centimetres and kilometres-to-miles pages, so they all live here now.

Every customary factor traces back to one inch

The inch is defined as exactly 0.0254 metres. That one definition, settled by the international yard and pound agreement of 1959, gives you all the others by multiplication, with no measuring involved:

1 in = 0.0254 m          (definition)
1 ft = 12 in  = 0.3048 m
1 yd = 36 in  = 0.9144 m
1 mi = 63360 in = 1609.344 m

The tool works its factors out the same way instead of storing a rounded 3.28 or 1.609. That matters at scale: convert a 10 km course with 1.609 instead of 1.609344 and the finish line ends up 2 metres out.

Look at the reciprocals and you can see which direction is tidy. Feet to metres terminates. One metre is 3.280839895… feet, a repeating decimal that never resolves, and that's why every quick rule of thumb for going to imperial is an approximation.

The nautical mile is the exception

It's the only unit here that doesn't come from the inch. A nautical mile is defined as exactly 1,852 metres, a round figure agreed in 1929 to approximate one minute of arc along a meridian. That's what makes it useful, since a degree of latitude is 60 of them.

Don't treat it as a rounded statute mile. One nautical mile is 1.1507794 statute miles, about 15% longer, and mixing the two up is a navigation error, not a rounding one.

Decimal feet are not feet and inches

This is the mistake that ruins a cut of timber. Convert 1.75 m and you get 5.7414698 ft. That's five feet and seventy-four hundredths of a foot. It is not five feet seven inches.

To get the carpenter's version, multiply the fractional part by twelve: 0.7414698 × 12 = 8.8976 in, so 1.75 m is 5 ft 8.9 in. This page has no feet-and-inches output, although an older version of this text said it did. If inches are what you want, pick inches as the target unit and read 68.8976 in.

The survey foot is a different foot

Until recently the United States kept a second foot, the survey foot, defined as 1200/3937 metres. It's larger than the international foot by two parts per million.

That sounds negligible, and mostly it is. Over 10 km the two definitions disagree by less than an inch. But on a state plane coordinate system with values in the millions of feet, the gap grows to metres. The survey foot was retired for new work at the end of 2022, though it's baked into decades of existing plats and geodetic data. This converter uses the international foot only, so if you're reading an older surveying document, check which foot it was drawn in before you trust anything here.

What this will not convert

Only lengths. Area and volume need the factor raised to a power, and doing that by eye is a common and expensive mistake. One square foot is 0.3048² = 0.09290304 square metres, not 0.3048. A cubic foot needs the cube. This page doesn't offer either, so work out the exponent yourself instead of converting a side length and hoping.

There's no fractional-inch output either. Imperial construction work is quoted in sixteenths and thirty-seconds, and this gives you decimals. The decimal to fraction converter can take it from there: set the denominator budget to 16 and it'll give you the nearest sixteenth, along with the error you're accepting.

More unit tools

• Weight Converter: kilograms, pounds, ounces and stone.
• Temperature Converter: four scales through a Celsius pivot.
• Percentage Calculator: for scaling a drawing up or down.