Length Converter
Convert inches, feet, yards and miles to millimeters, centimeters, meters and kilometers, and back, plus nautical miles, mils and more.
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- Result
- Formula
- Reverse
- Exact?
In Every Unit
| Unit | Value |
|---|
Saved Conversions
Conversions you add are saved in this browser.
| Note | Conversion | Remove |
|---|
How to Convert Length Units
Since 1959 the inch has been defined as exactly 2.54 centimeters, so every US customary length converts to metric exactly. Multiply by the factor to go from the first unit to the second; divide to go back.
cm = in × 2.54 m = ft × 0.3048 km = mi × 1.609344
Worked Example
Common Conversions
| From | Equals |
|---|---|
| 1 in | 2.54 cm |
| 1 cm | 0.3937008 in |
| 1 ft | 0.3048 m |
| 1 m | 3.28084 ft |
| 1 mi | 1.609344 km |
| 1 km | 0.6213712 mi |
| 1 mm | 0.03937008 in |
| 1 yd | 0.9144 m |
Unit Definitions
| Unit | Equals | Exact? |
|---|---|---|
| Nanometers (nm) | 1 × 10⁻⁹ m | Exact |
| Micrometers (microns) (µm) | 0.000001 m | Exact |
| Millimeters (mm) | 0.001 m | Exact |
| Centimeters (cm) | 0.01 m | Exact |
| Meters (m) | 1 m | Exact |
| Kilometers (km) | 1,000 m | Exact |
| Mils (thou) (mil) | 0.0000254 m | Exact |
| Inches (in) | 0.0254 m | Exact |
| Feet (ft) | 0.3048 m | Exact |
| Yards (yd) | 0.9144 m | Exact |
| Miles (mi) | 1,609.344 m | Exact |
| Nautical miles (nmi) | 1,852 m | Exact |
| Hands (hand) | 0.1016 m | Exact |
| Rods (rd) | 5.0292 m | Exact |
| Chains (ch) | 20.1168 m | Exact |
| Furlongs (fur) | 201.168 m | Exact |
| Fathoms (ftm) | 1.8288 m | Exact |
| Astronomical units (au) | 149,597,870,700 m | Exact |
| Light-years (ly) | 9.460730473 × 10¹⁵ m | Exact |
Factors follow NIST Special Publication 811, Appendix B. "Exact" means the unit is defined as that value; results are rounded only for display.
Tips
The US survey foot (1200/3937 m) was retired at the end of 2022; this page uses the international foot. A nautical mile is exactly 1,852 m, one minute of latitude.