Length units converter
Length units converter - converts units between kilometers, meters, decimeters, angstroms, miles, feet, inches, american/imperial units, nautical (sea) units and astronomical units
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What is "Length"?

The word "length" has several meanings (ex. the length of a word). We will focus on length in physical meaning in this article.

The definition of length:
LENGTH is the physical measure of distance between two points (according to measurements in the Euclidian space - so linear). The distance itself can be measured as a straight line, but also as a length of a curve.

The meaning of "length" could be equal to one of the following:
  • distance - most common: description of how far apart objects are. In strictly physical meaning - the length of way the object moves (possibly not the shortest way connecting two points)
  • displacement - the length of shortest possible way connecting two points
  • height - mostly in a vertical size of an object (like how "tall" it is)
  • altitude - when talking about how far in the air the object is (ex. how high is the airplane)
  • depth
  • width
  • size
Typically the symbol of length is L or l. Base unit is 1 meter. Length cannot be negative.

Length is measure of one dimension. However there is also area for 2 dimensions (length squared) and volume for 3 dimensions.


The meter (also called metre) is the base unit of length in SI. It is defined as the distance travelled by light in vacuum during a time interval of 1/299.792.458 of a second. It has been defined on 17th General Conference on Weights and Measures in 1983.

After thousands of years of distance measurements, the thousands of units has been defined. The most known units we found are:
  • meter - and metric dependent units like kilometer, decimeter, centimeter, milimeter, micrometer, nanometer, angstrom etc. - the decimal multiples and submultiples of meter (so, thousands, milions... of meters) according to SI defined prefixes
  • mile, yard, foot, fathom, inch and less known league, furlong, chain, rod, link, hand, line - british (imperial) and american(US) units
  • parsec, astronomical unit - dedicated for astronomy
  • light year, light minute and light second - the distance travelled by light in vacuum during given unit of time (a year, minute, second etc.). These are really big lengths, so also used mainly for astronomical measurements.
  • sea league, sea mile, cabel (british or american) - are nautical (sea realated) units.

How to convert

  • Enter the number to field "value" - enter the NUMBER only, no other words, symbols or unit names. You can use dot (.) or comma (,) to enter fractions.
    • 1000000
    • 123,23
    • 999.99999
  • Find and select your starting unit in field "unit". Some unit calculators have huge number of different units to select from - it's just how complicated our world is...
  • And... you got the result in the table below. You'll find several results for many different units - we show you all results we know at once. Just find the one you're looking for.

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