Distance and length measurements from atomic and manufacturing scales through surveying and astronomy.
All factors come from the central conversion registry.
| Unit | Symbol | System | Definition |
|---|---|---|---|
| Nanometer | nm | SI | 1 nm = 10⁻⁹ m |
| Micrometer | µm | SI | 1 µm = 10⁻⁶ m |
| Picometer | pm | SI | 1 pm = 10⁻¹² m |
| Ångström | Å | Scientific | 1 Å = 10⁻¹⁰ m |
| Mil | mil | US | 1 mil = 0.001 in = 0.0000254 m |
| Millimeter | mm | SI | 1 mm = 0.001 m |
| Centimeter | cm | SI | 1 cm = 0.01 m |
| Inch | in | International/US | 1 in = exactly 0.0254 m |
| Hand | hand | Imperial/Equestrian | 1 hand = exactly 4 in = 0.1016 m |
| Link | li | Survey | 1 link = 0.201168 m |
| Foot | ft | International/US | 1 ft = exactly 0.3048 m |
| Yard | yd | International/US | 1 yd = exactly 0.9144 m |
| Fathom | ftm | Maritime | 1 fathom = 1.8288 m |
| Rod | rd | Survey/Imperial | 1 rod = 5.0292 m |
| Meter | m | SI | 1 m = 1 m |
| Chain | ch | Survey | 1 chain = 20.1168 m |
| Furlong | fur | Imperial | 1 furlong = 201.168 m |
| Kilometer | km | SI | 1 km = 1000 m |
| Mile | mi | International/US | 1 mi = exactly 1609.344 m |
| Nautical Mile | nmi | Maritime | 1 nmi = exactly 1852 m |
| League | lea | Historical/Conventional | 1 league = 3 mi = 4,828.032 m |
| Astronomical Unit | AU | Astronomy | 1 AU = exactly 149,597,870,700 m |
| Light-year | ly | Astronomy | 1 ly = 9.4607304725808×10¹⁵ m |
| Parsec | pc | Astronomy | ≈ 3.085677581491367×10¹⁶ m |
Length conversions use one base dimension and standards-defined relationships. International inches, feet, yards and miles are tied exactly to the meter, while SI prefixes scale by powers of ten.
The interactive calculator, reference table and indexed pair pages all read from the same conversion registry, so unit definitions and formulas stay synchronized.
Length is one of the most common physical quantities converted between metric/SI and international or US customary units. Metric units such as millimeters, centimeters, meters and kilometers scale by powers of ten. International inches, feet, yards and miles have exact relationships to the meter.
For example, 1 inch = exactly 25.4 mm, 1 foot = exactly 0.3048 m and 1 mile = exactly 1609.344 m. Use the same converter for either direction.