Length and distance conversions

length conversions
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Select a unit of length

What is length? What is distance?

Definition: Length is a physical property that expresses (quantitatively) how long something is; distance shows how far away something is. The base unit of length in the International System of Units (SI) is the metre (or meter, US spelling). Common units of length / distance currently in use include nanometers (nm), micrometers (µm), millimeters (mm), centimeters (cm), kilometers (km), miles (mi), inches (in), feet (ft), yards (yd) and light-years (ly).

Common length conversions

  • 1 meter = 100 centimeters = 1,000 millimeters
  • 1 kilometer = 1,000 meters
  • 1 mile = 1,609.344 meters = 5,280 feet
  • 1 nautical mile = 1,852 meters = 1.852 kilometers
  • 1 mile = 0.868976 nautical miles
  • 1 foot = 0.3048 meters = 12 inches
  • 1 yard = 0.9144 meters = 3 feet
  • 1 inch = 2.54 centimeters = 0.0254 meters
  • 1 angstrom = 10-10 meters = 0.1 nanometers
  • 1 light-year = 0.306595 parsecs

Subdivisions and multiples of the meter using SI prefixes

Subdivisions of the meter Multiples of the meter
Name Symbol Value Name Symbol Value
decimeter dm 10-1 m decameter dam 101 m
centimeter cm 10-2 m hectometer hm 102 m
millimeter mm 10-3 m kilometer km 103 m
micrometer μm 10-6 m megameter Mm 106 m
nanometer nm 10-9 m gigameter Gm 109 m
picometer pm 10-12 m terameter Tm 1012 m
femtometer fm 10-15 m petameter Pm 1015 m
attometer am 10-18 m exameter Em 1018 m
zeptometer zm 10-21 m zettameter Zm 1021 m
yoctometer ym 10-24 m yottameter Ym 1024 m