Length Unit Converter
Convert between metric and imperial units of length and distance — and, in a separate category, astronomical distances — using exact, standards-based conversion factors. The result updates as you type.
Conversion reference
| From | To | Result |
|---|---|---|
| 1 m | Foot (ft) | 3.28083989501 ft |
| 1 m | Inch (in) | 39.3700787402 in |
| 1 m | Centimeter (cm) | 100 cm |
| 1 m | Yard (yd) | 1.09361329834 yd |
| 1 km | Mile (mi) | 0.621371192237 mi |
| 1 km | Nautical mile (nmi) | 0.539956803456 nmi |
| 1 in | Centimeter (cm) | 2.54 cm |
| 1 in | Millimeter (mm) | 25.4 mm |
| 1 mi | Kilometer (km) | 1.609344 km |
| 1 mi | Meter (m) | 1609.344 m |
Values are generated by the converter engine, at Auto precision.
About this converter
This tool converts a length from one unit to another by expressing both in metres and taking the ratio. Every everyday factor here is exact by definition: the inch is 25.4 mm, the foot is 0.3048 m, the yard is 0.9144 m, the mile is 1609.344 m, and the nautical mile is 1852 m.
The Astronomical category keeps very large units — the astronomical unit (149,597,870,700 m exactly), the light-year, and the parsec — apart from millimetres and inches so the dropdowns stay usable.
How to use it
- Pick a category if you need astronomical distances; otherwise stay on Length.
- Type the value you want to convert in the Value field.
- Choose the unit you are converting from and the unit you want the answer in.
- Read the result, press Copy result, or press Swap to reverse the direction.
- Change Precision to Auto for full accuracy or to a fixed number of decimals for a tidy display.
The result updates as you type — there is no Calculate button. Use Swap to reverse the two units, and Reset to return to the defaults.
Formula and common values
value_in_target = value_in_source × (source_factor ÷ target_factor), where each factor is the unit’s size in metres.
- 1 meter = 3.280839895013123 feet = 39.37007874015748 inches
- 1 kilometer = 0.621371192237334 miles = 0.5399568034557235 nautical miles
- 1 inch = 2.54 centimeters = 25.4 millimeters (exact)
- 1 mile = 1.609344 kilometers (exact)
FAQ
How many feet are in a meter?
One meter is exactly 1 / 0.3048 feet, which is about 3.280839895 feet. The foot is defined as 0.3048 meters exactly (international yard and pound agreement, 1959), so the conversion is exact by definition.
Is one inch exactly 2.54 centimeters?
Yes. The international inch is defined as 25.4 millimeters exactly, so 1 inch = 2.54 cm exactly, with no rounding.
Why are light-years and parsecs in a separate category?
Astronomical distances are many orders of magnitude larger than everyday lengths, so mixing them into the same dropdown makes the list hard to use and the results hard to read. The Astronomical category keeps metres, kilometres, astronomical units, light-years, and parsecs together.
What is a mil?
A mil (also called a thou) is one thousandth of an inch, 0.0254 mm. It is common in manufacturing and PCB design. It is not a millimetre.
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