Length Converter
This length converter changes a distance between thirteen units: micrometers, millimeters, centimeters, decimeters, meters and kilometers, plus thou (mil), inches, feet, yards, furlongs, miles and nautical miles. Enter a number, pick the unit you have and the one you want, and the table under the result shows the same length in every unit, from a TV screen in inches to a race in kilometers.
Updated
Results
- Unit
- Conversion factorOne unit of the source expressed in the target unit
| Unit | Value |
|---|
Results are estimates. See the methodology below.
How to use the converter
- Enter the value. Decimals are fine, for example 5.75 or 0.5.
- From: the unit you are starting with, such as in.
- To: the unit you need, such as cm.
You get the converted value and the factor for one unit (for example 1 mi = 1.609344 km). The table lists your value in all thirteen units. The converter takes a single number, so for a height such as 5 ft 10 in, convert it to inches first (5 × 12 + 10 = 70 in), or enter 5.8333 ft.
Conversion factors
Every conversion passes through the meter: the value is multiplied by the size of the source unit in meters and divided by the size of the target unit. US customary lengths are defined exactly in metric terms, so none of these factors is an approximation.
| Unit | Definition | Exact value |
|---|---|---|
| thou (mil) | 0.001 in | 25.4 µm |
| in (inch) | international inch | 2.54 cm |
| ft (foot) | 12 in | 0.3048 m |
| yd (yard) | 3 ft | 0.9144 m |
| fur (furlong) | 660 ft = 1/8 mi | 201.168 m |
| mi (mile) | 5,280 ft | 1,609.344 m |
| nmi (nautical mile) | international nautical mile | 1,852 m |
The calculation keeps 12 significant digits and the result shows up to 10. The foot used here is the international foot. The older US survey foot, slightly longer, was declared obsolete by NIST from January 1, 2023. With the survey foot defined as 1200/3937 m, the old survey mile was about 1,609.3472 m, roughly 3 mm longer than the international mile.
Examples
1. Height in feet and inches
| Height | Inches | Centimeters |
|---|---|---|
| 5 ft 5 in | 65 in | 165.1 cm |
| 5 ft 9 in | 69 in | 175.26 cm |
| 5 ft 10 in | 70 in | 177.8 cm |
Going the other way, 180 cm is 70.87 in, just under 5 ft 11 in.
2. Race distances
A 5K is 3.1069 miles and a 10K is 6.2137 miles. A 42.195 km marathon is 26.2188 miles; note that 26.2 miles is 42.1648 km, so the round figure is a little short.
3. Screens and small measurements
TV and monitor sizes are diagonals in inches: a 55-inch screen measures 139.7 cm corner to corner, a 65-inch one 165.1 cm. A 6.5-inch phone screen is 165.1 mm. At the small end, 4 mil, a thickness often printed on plastic sheeting, is 101.6 µm, or 0.1016 mm.
Miles on land and at sea
The ordinary mile, sometimes called the statute mile, is 5,280 ft. The nautical mile used at sea and in aviation is defined as exactly 1,852 m, so it is longer: 1 nautical mile = 1.1508 miles = 6,076.12 ft. Speeds in knots are nautical miles per hour. The furlong, 1/8 of a mile, survives mainly in horse racing. Be careful with the word “mil”: in this converter it is a thousandth of an inch, not a millimeter.
Frequently asked questions
How many centimeters are in an inch?
Exactly 2.54 cm, by definition. To convert inches to centimeters, multiply by 2.54; to go back, multiply by 0.3937. A 12-inch ruler is 30.48 cm long.
How many feet are in a meter?
One meter is 3.28084 ft, or 39.37 in. One foot is exactly 0.3048 m, so 100 yd is 91.44 m.
How do I convert kilometers to miles?
Multiply by 0.621371. For miles to kilometers, multiply by 1.609344. A quick estimate: divide kilometers by 1.6. 100 km/h is about 62 mph.
How many feet are in a mile?
5,280 ft, which is also 1,760 yd, 63,360 in and 1,609.344 m.
What is a thou or mil?
One-thousandth of an inch, exactly 25.4 micrometers (0.0254 mm). Machinists usually call it a thou; the same unit is called a mil for coatings, films and wire.
How long is a nautical mile?
Exactly 1,852 meters, which is 1.15078 miles or about 6,076 ft. It is the unit used in navigation, at sea and in the air.
Sources
Conversions use the exact definitions listed on this page and are rounded for display. For engineering, construction or legal surveys, follow the units and tolerances your specifications require.