Length Converter - Feet, Inches, Centimetres, Metres, Kilometres and Miles

Each unit is stored as an exact fraction of a metre, and a conversion multiplies by the size of the unit you have and divides by the size of the unit you want. This is done with whole-number arithmetic, not floating point, so nothing drifts and a conversion followed by its reverse gives back the number you typed. The answer is rounded only when it is shown. The Auto setting shows an exact answer in full when it fits in 14 digits and otherwise rounds to 10 significant digits, and you can pick 4, 6, 8 or 12 digits instead.

The inch-based units come from the 1959 international yard and pound agreement. An inch is exactly 25.4 mm, so a foot (12 inches) is exactly 0.3048 m, a yard (3 feet) is 0.9144 m and a mile (1,760 yards) is 1,609.344 m. NIST Handbook 44, NIST SP 811 and the UK Weights and Measures Act 1985 all give these values. The older US survey foot (1200/3937 m) is about 2 parts per million longer, which is 2 mm in a kilometre. NIST asks people to stop using it from 1 January 2023, and this page does not use it. The nautical mile is exactly 1,852 m.

The rod (also called a pole or a perch), the chain and the furlong are land-surveying lengths. A rod is 16.5 feet, a chain is 66 feet (4 rods) and a furlong is 660 feet (10 chains). Square one rod and you get the perch used to measure land in Sri Lanka, which the area converter covers.

To change a height from feet and inches to centimetres, turn it all into inches (feet x 12 + inches) and multiply by 2.54. To go the other way, divide the centimetres by 2.54 and split the inches into whole feet and a remainder. The helper under the converter does both and shows the remainder in inches rounded to one decimal place. It is handy for forms that ask for your height in centimetres.