Basic Measurements
Length & Distance Converter
Length measures how far something extends in one dimension. The SI base unit is the metre, from which the kilometre, centimetre and millimetre derive; the imperial system instead uses the foot, inch and mile.
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About this category: Length & Distance
Length measures how far something extends in one dimension. The SI base unit is the metre, from which the kilometre, centimetre and millimetre derive; the imperial system instead uses the foot, inch and mile.
Length units describe structural dimensions and distances; note that a foot is exactly 0.3048 m and an inch exactly 25.4 mm.
Practical uses
- Engineering dimensions and structural member lengths
- Machining, joinery and part tolerances
- Road distances and air/sea navigation
Available units
| Unit | Name | Definition | Classification |
|---|---|---|---|
| m | Meter | The metre is the SI base unit of length. | SI Base |
| km | Kilometer | One thousand metres, used for long distances. | SI Derived |
| cm | Centimeter | One hundredth of a metre. | SI Derived |
| mm | Millimeter | One thousandth of a metre, common in technical drawings. | SI Derived |
| Β΅m | Micrometer | One millionth of a metre, used for fine measurement. | SI Derived |
| nm | Nanometer | One billionth of a metre, used in nanotechnology. | SI Derived |
| mi | Mile | The international mile equals exactly 1609.344 metres. | Non-SI |
| yd | Yard | Three feet, exactly 0.9144 metres. | Non-SI |
| ft | Foot | The international foot equals exactly 0.3048 metres. | Non-SI |
| in | Inch | The international inch equals exactly 25.4 millimetres. | Non-SI |
| nmi | Nautical Mile | 1852 metres, used in marine and air navigation. | Non-SI |
| cubit | Cubit (common approximation) | An ancient length unit of about 0.4572 metres. | Traditional |
| league | League (common standard) | A historical distance of about three miles. | Traditional |
| ly | Light Year | The distance light travels in one year. | Non-SI |
| AU | Astronomical Unit | The mean EarthβSun distance. | Accepted with SI |
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