Unit Conversion

Convert numbers between two units quickly and precisely

Length Converter


Unit Conversion

Convert length units: meters, inches, miles, and astronomical distances

The length converter accurately converts values between the metric system (meter, kilometer, decimeter, centimeter, millimeter, micrometer, nanometer, ångström) and the imperial/US system (inch, foot, yard, mile, nautical mile). For astronomical distances, light-year, parsec, and the astronomical unit (AU) are also available.

Key conversion factors:

  • 1 kilometer (km) = 1,000 meters (m) – base unit of the metric system
  • 1 mile (mi) = 1.609 kilometers – used for distances in the US and UK
  • 1 foot (ft) = 30.48 centimeters – standard measurement in aviation and construction
  • 1 inch (in) = 2.54 centimeters – common for screen diagonals, thread sizes, and pipe diameters
  • 1 nautical mile (nmi) = 1.852 kilometers – reference unit in shipping and aviation
  • 1 astronomical unit (AU) ≈ 149.6 million kilometers – average Earth–Sun distance
  • 1 parsec (pc) ≈ 30.86 trillion kilometers ≈ 3.26 light-years – common in professional astronomy
  • 1 light-year (ly) ≈ 9.461 trillion kilometers – popular astronomy distance measure

Applications:

  • Travel & navigation: converting map scales and GPS distances between kilometers and miles
  • Trades & construction: converting inch-based nominal sizes (tools, threads, pipes) to metric values
  • Natural sciences: wavelengths in nanometers and Ã¥ngström, cosmic distances in light-years and parsecs
  • Display technology: converting screen diagonals from inches to centimeters

The length converter delivers exact results for trip planning, technical drawings, and scientific calculations alike. For physical quantities built on length – such as speed or acceleration – see the speed converter and acceleration converter.


Frequently asked questions about converting length

1 mile (mi) equals 1.609344 kilometers. Conversely, 1 kilometer is about 0.621 miles. This conversion is especially relevant for US or British distance figures.

A nautical mile (nmi) equals 1.852 kilometers and is based on one arcminute of Earth's circumference – it's used in shipping and aviation. A statute mile (mi), on the other hand, equals 1.609344 kilometers and comes from the imperial system. So both are different units with different origins.

A light-year equals about 9.461 trillion kilometers (9.461 * 10^15 meters) – the distance light travels in one year in a vacuum. For even larger astronomical distances, the parsec is often used, which equals about 3.26 light-years.