How many astronomical units are in one light-year?

One light-year equals 63,241.077084 AU. The formula is AU = ly × 63,241.077084.

How do I convert light-years to astronomical units?

Multiply the value in light-years by 63,241.077084. For example, 100 × 63,241.077084 = 6,324,107.708427 — so 100 ly = 6,324,107.708427 AU.

How many light-years are in one astronomical unit?

One astronomical unit equals 0.000016 ly.

Pair · linear · factor 63,241.077084

light-years to astronomical units

lyAU

Active unit

light-years · ≈ 946,073,047,258,080.1 km (base)

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An emerald parallax triangle with a star at its apex and a scale of cosmic distances, against a cosmic nebula in violet and magenta

Astronomical distances

A light-year is not time — how we measure the cosmos

Han Solo bragged he made the Kessel Run in less than twelve parsecs — but a parsec is a unit of distance, not time. We make the same slip with the light-year. Here is how astronomy handles distances that will not fit on Earth — and why our brains stumble over them.

12 min