# Convert Light second to...

Light second | |
---|---|

Unit system | astronomical |

Unit of | length |

Unit conversions | |

1 light second in ... |
... is equal to ... |

SI unit(s) | 2.998×10^{5} km |

Imperial/US unit(s) | 1.863×10^{5} mi |

**I want to convert:**
**using**

Metric | Conversion |
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Kilometre [km] | |

Hectometre [hm] | |

Decametre [dam] | |

Metre [m] | |

Decimetre [dm] | |

Centimetre [cm] | |

Millimetre [mm] | |

Micrometre [µm] | |

Nanometre [nm] | |

Angstrom [Å] |

British/Imperial | Conversion |
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League | |

Mile [mi] | |

Furlong | |

Chain | |

Rod [rd] | |

Yard [yd] | |

Foot [ft] | |

Link | |

Hand | |

Inch [in] | |

Line | |

Mil [mil] | |

Thou [thou] |

Nautical | Conversion |
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Sea mile | |

Fathom |

Astronomical | Conversion |
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Parsec [pc] | |

Light Year | |

Astronomical Unit [AE] | |

Light Minute | |

Light Second |

The **light-second** is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in one second, and is equal to exactly 299792458 metres (just over 186282 miles).

Just as the second forms the basis for other units of time, the **light-second** can form the basis for other units of length, ranging from the light-nanosecond (just under one international foot) to the light-minute, light-hour and light-day, which are sometimes used in popular science publications. The more commonly used light-year is also presently defined to be equal to precisely 31557600 light-seconds, since the definition of a year is based on a Julian year (not Gregorian year) of exactly 365.25 days, each of exactly 86400 SI seconds.

This article uses material from the Wikipedia article "Light-second", which is released under the Creative Commons Attribution-Share-Alike License 3.0.