Available Length units
- metre conversions
The metre is the SI base unit of length. It is used globally in science, engineering, geography, and everyday measurement as the standard reference for distance.
- kilometre conversions
A kilometre is a metric unit of length equal to 1,000 metres. It is the standard unit for road distances, route planning, and geographic measurements in most countries.
- centimetre conversions
A centimetre is a metric unit of length equal to one hundredth of a metre. It is commonly used for everyday measurements such as clothing sizes, body height, and small object dimensions.
- millimetre conversions
A millimetre is a metric unit of length equal to one thousandth of a metre. It is used in precision manufacturing, medical imaging, engineering tolerances, and detailed technical specifications.
- inch conversions
An inch is a unit of length in imperial and US customary systems equal to 1/12 of a foot. It is widely used for screen sizes, display resolutions, pipe diameters, and small-scale measurements in everyday contexts.
- foot conversions
A foot is a unit of length in imperial and US customary systems equal to 12 inches. It is commonly used in construction, architecture, body height measurements, and aviation for altitude references.
- mile conversions
A mile is a unit of length commonly used in the United States and the United Kingdom for road distance and travel-related measurements.
- yard conversions
A yard is a unit of length used mainly in imperial and US customary measurement systems. It is often used for shorter distances in sports, construction, landscaping, and fabric measurement.
- micrometre conversions
A micrometre, also called a micron, is a unit of length equal to one millionth of a metre. It is used in microscopy, semiconductor fabrication, and the measurement of fine particles and biological cells.
- nanometre conversions
A nanometre is a unit of length equal to one billionth of a metre. It is used to measure wavelengths of visible light, atomic radii, and dimensions of nanostructures in materials science.
Full Length conversion matrix
| Unit | Equivalent in metres | m | km | cm | mm | in | ft | mi | yd | µm | nm |
|---|---|---|---|---|---|---|---|---|---|---|---|
| metre | 1 m | 1 | 0.001 | 100 | 1,000 | 39.37007874 | 3.2808399 | 0.00062137 | 1.0936133 | 1,000,000 | 999,999,999.99999988 |
| kilometre | 1,000 m | 1,000 | 1 | 100,000 | 1,000,000 | 39,370.07874016 | 3,280.83989501 | 0.62137119 | 1,093.61329834 | 1.000000e+09 | 1.000000e+12 |
| centimetre | 0.01 m | 0.01 | 0.00001 | 1 | 10 | 0.39370079 | 0.0328084 | 0.00000621 | 0.01093613 | 10,000 | 10,000,000 |
| millimetre | 0.001 m | 0.001 | 0.000001 | 0.1 | 1 | 0.03937008 | 0.00328084 | 6.213712e-07 | 0.00109361 | 1,000 | 1,000,000 |
| inch | 0.0254 m | 0.0254 | 0.0000254 | 2.54 | 25.4 | 1 | 0.08333333 | 0.00001578 | 0.02777778 | 25,400 | 25,400,000 |
| foot | 0.3048 m | 0.3048 | 0.0003048 | 30.48 | 304.8 | 12 | 1 | 0.00018939 | 0.33333333 | 304,800 | 304,800,000 |
| mile | 1,609.344 m | 1,609.344 | 1.609344 | 160,934.4 | 1,609,344 | 63,360 | 5,280 | 1 | 1,760 | 1.609344e+09 | 1.609344e+12 |
| yard | 0.9144 m | 0.9144 | 0.0009144 | 91.44 | 914.4 | 36 | 3 | 0.00056818 | 1 | 914,400 | 914,399,999.99999988 |
| micrometre | 0.000001 m | 0.000001 | 1.000000e-09 | 0.0001 | 0.001 | 0.00003937 | 0.00000328 | 6.213712e-10 | 0.00000109 | 1 | 1,000 |
| nanometre | 1.000000e-09 m | 1.000000e-09 | 1.000000e-12 | 1.000000e-07 | 0.000001 | 3.937008e-08 | 3.280840e-09 | 6.213712e-13 | 1.093613e-09 | 0.001 | 1 |
About Length
Linear distance units
Real-world uses
Length measurements underpin nearly every physical discipline. Architects and engineers specify building dimensions in metres or feet, while machinists work in thousandths of an inch for precision parts. Shipping and logistics rely on kilometres and nautical miles for route planning, and textile industries measure fabric in yards or metres. Even smartphone screens are sized in inches diagonally, demonstrating how length units permeate consumer products as much as heavy industry.
History
Ancient civilisations based length on body parts: the Egyptian cubit (forearm length), the Roman foot, and the English yard (nose-to-thumb span of Henry I). The French Revolution introduced the metre in 1799, originally defined as one ten-millionth of the distance from the equator to the North Pole along a meridian through Paris. In 1983, the metre was redefined using the speed of light, fixing it as the distance light travels in 1/299,792,458 of a second.
Common mistakes
A frequent error is confusing miles with kilometres when reading foreign road signs or race distances, since a mile is roughly 1.6 km. Another pitfall is mixing up nautical miles (1,852 m) with statute miles (1,609 m) in aviation and maritime contexts. People also sometimes treat feet and inches as a decimal system, writing 5.8 feet when they mean 5 feet 8 inches.
Measurement standards
The metre is one of seven SI base units, maintained by the International Bureau of Weights and Measures (BIPM). Since 2019, it is defined by fixing the numerical value of the speed of light in vacuum to exactly 299,792,458 metres per second.
Did you know?
A human hair is roughly 70 micrometres wide, while a single gold atom measures about 0.144 nanometres in diameter — meaning you could line up nearly half a million atoms across the width of one hair.
Common values
| metres | kilometres | |
|---|---|---|
| Height of a door | 2.1 metres | 0.0021 kilometres |
| Basketball court length | 28 metres | 0.028 kilometres |
| Football field (soccer) | 105 metres | 0.105 kilometres |
| Marathon distance | 42,195 metres | 42.195 kilometres |
| Altitude of a cruising airplane | 10,668 metres | 10.668 kilometres |