Length Converter

Metres, centimetres, millimetres, kilometres, inches, feet, yards, miles and nautical miles, converting between any pair. This page absorbed the separate metres-to-feet, inches-to-centimetres and kilometres-to-miles pages, so all of them now live in one place.

Every customary factor traces back to one inch

The inch is defined as exactly 0.0254 metres. That single line, settled by the international yard and pound agreement of 1959, generates all the others by multiplication rather than by measurement:

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 derives its factors that way rather than storing a rounded 3.28 or 1.609. It matters at scale: converting a 10 km course with 1.609 instead of 1.609344 puts the finish line 2 metres out.

Read 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, which is why every quick-conversion rule of thumb in the imperial direction is an approximation.

The nautical mile is the exception

It is the one unit here that does not descend 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 — which is what makes it useful, since a degree of latitude is 60 of them.

It is not a rounded statute mile. One nautical mile is 1.1507794 statute miles, about 15% longer, and mixing the two is a navigation error rather than a rounding one.

Decimal feet are not feet and inches

This is the mistake that costs a cut of timber. Convert 1.75 m and the answer is 5.7414698 ft. That is five feet and seventy-four hundredths of a foot — 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. There is no feet-and-inches output on this page, and an older version of this text claimed there was; if inches are what you want, select inches as the target unit directly and read 68.8976 in.

The survey foot is a different foot

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

That sounds negligible and mostly is — over 10 km the two definitions disagree by less than an inch. Over a state plane coordinate system with values in the millions of feet, it becomes metres. The survey foot was retired for new work at the end of 2022, but it is baked into decades of existing plats and geodetic data. This converter uses the international foot only. If you are reading an older surveying document, check which one it was drawn in before trusting anything here.

What this will not convert

Only lengths. Area and volume need the factor raised to a power, and doing it by eye is a common and expensive error: one square foot is 0.3048² = 0.09290304 square metres, not 0.3048. A cubic foot needs the cube. Neither is offered on this page, so do the exponent yourself rather than converting a side length and hoping.

There is also no fractional-inch output. Imperial construction work is quoted in sixteenths and thirty-seconds, and this returns decimals. The decimal to fraction converter takes it from there — set the denominator budget to 16 and it will give you the nearest sixteenth along with the error you are accepting.

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