Length Converter
Convert between 13 units of length — metric, imperial, and astronomical. From nanometers to light years, all conversions use exact SI-defined constants.
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About the Length Converter
Length is one of the seven SI base quantities. The metric system uses the meter as its base unit, defined since 2019 as the distance light travels in 1/299,792,458 of a second. The imperial system, still widely used in the US, uses feet and inches. Our converter supports 13 units ranging from nanometers (used in semiconductor manufacturing) to light years (used in astronomy).
Quick facts
- ›One light year equals approximately 9.461 trillion kilometres
- ›The meter was originally defined as 1/10,000,000 of the distance from equator to North Pole
- ›A nautical mile (1,852 m) is based on one arcminute of latitude along a meridian
- ›The smallest length with physical meaning is the Planck length: ~1.616 × 10⁻³⁵ m
Common uses: Construction, engineering, manufacturing, textiles, navigation, astronomy, physics