Unit-To-Unit Distance conversion

Light-Years to Kilometres

1 light-year = 9460730472580.80078125 kilometres

A light-year is 9.4607 trillion kilometres. The nearest star system, Alpha Centauri, is 4.37 light-years away, or about 41 trillion km.

Formula km = ly × 9460730472580.80078125

=

Type in either field — the other updates on every keystroke. Need other units? Open the full distance converter.

Light-Years to Kilometres — quick reference
Light-yearKilometre
1 ly9460730472580.800781 km
2 ly18921460945161.601563 km
3 ly28382191417742.398438 km
4 ly37842921890323.203125 km
5 ly47303652362904 km
10 ly94607304725808 km
15 ly141910957088712 km
20 ly189214609451616 km
25 ly236518261814520 km
50 ly473036523629040 km
100 ly946073047258080 km
500 ly4730365236290400 km
1000 ly9460730472580800 km
Kilometres to Light-Years — reverse
KilometreLight-year
1 km1.057001e-13 ly
2 km2.114002e-13 ly
3 km3.171003e-13 ly
4 km4.228003e-13 ly
5 km5.285004e-13 ly
10 km1.057001e-12 ly
15 km1.585501e-12 ly
20 km2.114002e-12 ly
25 km2.642502e-12 ly
50 km5.285004e-12 ly
100 km1.057001e-11 ly
500 km5.285004e-11 ly
1000 km1.057001e-1 ly

Worked examples

Common values
SituationFromTo
One light-year1 ly9.461 × 1012 km
Proxima Centauri4.25 ly4.021 × 1013 km
Sirius8.6 ly8.136 × 1013 km
Vega25 ly2.365 × 1014 km
Centre of the Milky Way26,000 ly2.460 × 1017 km
Andromeda galaxy2,500,000 ly2.365 × 1019 km

Mental-math shortcut

Multiply by 9.46 trillion, which is 9.46 × 10¹² km. One light-year is also about 63,241 AU.

Where this conversion comes up

Distances to stars and galaxies are given in light-years. Proxima Centauri, the nearest star, lies about 4.0 × 10¹³ km away.

Common mistakes

A light-year is a distance, not a time, so "light-years ago" is wrong. Do not mix it up with the parsec, which is about 3.26 light-years.

Background

A light-year is the distance light travels in a vacuum in one Julian year of 365.25 days, which is exactly 9,460,730,472,580,800 metres.

Frequently asked

How many kilometres are in a light-year?
1 light-year = 9460730472580.80078125 kilometres. In the other direction, 1 kilometre = 1.057000834e-13 light-years.
What is a light-year?
A light-year is the distance light travels in vacuum in one Julian year: 9,460,730,472,580.8 kilometres. It is a distance, not a time.
What is a kilometre?
A kilometre is 1,000 metres, the standard road-distance unit for most of the world.
How many kilometres is a light-year?
About 9.4607 trillion km (9.4607 × 10¹² km).

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Miles to Kilometres Kilometres to Miles Nautical Miles to Kilometres Nautical Miles to Miles Astronomical Units to Kilometres Metres to Miles