Popular length conversions
Length units
Length measures distance in one dimension. The SI base unit is the meter, defined by the distance light travels in a vacuum in 1/299,792,458 of a second. Since the 1959 international yard and pound agreement, imperial and US customary lengths are defined exactly in meters: an inch is exactly 2.54 centimeters.
| Unit | Symbol | In meters | Definition |
|---|---|---|---|
| Nanometer | nm | 1 × 10⁻⁹ m | One billionth of a meter, used for wavelengths of light and semiconductor feature sizes. |
| Micrometer | µm | 0.000001 m | One millionth of a meter, also called a micron. |
| Millimeter | mm | 0.001 m | One thousandth of a meter. Ten millimeters make a centimeter. |
| Centimeter | cm | 0.01 m | One hundredth of a meter. An inch is exactly 2.54 centimeters. |
| Decimeter | dm | 0.1 m | One tenth of a meter. |
| Meter | m | 1 m | The SI base unit of length, defined by the speed of light. |
| Kilometer | km | 1,000 m | One thousand meters. A mile is about 1.609 kilometers. |
| Inch | in | 0.0254 m | Exactly 2.54 centimeters. Twelve inches make a foot. |
| Foot | ft | 0.3048 m | Exactly 0.3048 meters, or 12 inches. Three feet make a yard. |
| Yard | yd | 0.9144 m | Exactly 0.9144 meters, or 3 feet. |
| Mile | mi | 1,609.344 m | Exactly 1,609.344 meters, or 5,280 feet. |
| Nautical mile | nmi | 1,852 m | Exactly 1,852 meters. Used in air and sea navigation; one knot is one nautical mile per hour. |
| Mil | mil | 0.0000254 m | One thousandth of an inch, used for wire and sheet thickness. |
| Hand | hh | 0.1016 m | Four inches, traditionally used to measure the height of horses. |
| Fathom | ftm | 1.8288 m | Six feet, used for water depth. |
| Furlong | fur | 201.168 m | An eighth of a mile, or 660 feet, still used in horse racing. |
| Ångström | Å | 1 × 10⁻¹⁰ m | One ten-billionth of a meter, used for atomic scales. |
| Astronomical unit | au | 149,597,870,700 m | Exactly 149,597,870,700 meters, roughly the mean Earth to Sun distance. |
| Light-year | ly | 9.460730473 × 10¹⁵ m | The distance light travels in one Julian year: exactly 9,460,730,472,580,800 meters. |
| Parsec | pc | 3.085677581 × 10¹⁶ m | About 3.26 light-years, defined from the astronomical unit and one arcsecond of parallax. |
Calculate with length
The smart calculator does arithmetic across length units and picks a sensible unit for the answer. Try 5 ft 11 in to cm.
Questions and answers
Which length units can I convert?
All 20: nanometers, micrometers, millimeters, centimeters, decimeters, meters, kilometers, inches, feet, yards, miles, nautical miles, mils, hands, fathoms, furlongs, ångströms, astronomical units, light-years, parsecs.
What is the SI unit of length?
This converter uses the meter (m) as its base unit. Length measures distance in one dimension. The SI base unit is the meter, defined by the distance light travels in a vacuum in 1/299,792,458 of a second. Since the 1959 international yard and pound agreement, imperial and US customary lengths are defined exactly in meters: an inch is exactly 2.54 centimeters.
How many centimeters are in a foot?
A foot is exactly 30.48 centimeters, because an inch is defined as exactly 2.54 cm and a foot is 12 inches.
How precise are the results?
Factors are the exact legal definitions where one exists (an inch is exactly 2.54 cm, a pound exactly 0.45359237 kg). Results show 10 significant digits by default; the precision menu offers 4 to 15.
Does the length converter work offline?
Yes. ConvertEasy is a progressive web app: after your first visit it keeps working with no connection, and you can install it to your home screen from the browser menu.