Light Year Converter: LY, AU & Kilometers Distance Tool

Cosmic Distance Converter

Convert between astronomical units, light years, and kilometers to understand the vast scales of our universe.

Value

From Unit

Light Years 1.0000e+0

AU 6.3241e+4

Kilometers 9.4610e+12

Measuring the Universe

Distances in space are so vast that conventional units like kilometers or miles become impractical. Astronomers use specialized units to describe the scale of the cosmos.

Common Units

Light Year (ly): The distance light travels in a vacuum in one year, approximately 9.46 trillion kilometers.
Astronomical Unit (AU): The average distance between the Earth and the Sun, roughly 150 million kilometers.
Parsec (pc): Another unit used for even larger distances, equivalent to about 3.26 light years.

Frequently Asked Questions (FAQ)

How far is the nearest star?

Proxima Centauri, the closest star to our Sun, is about 4.24 light years away.

How many AU are in a light year?

There are approximately 63,241 Astronomical Units in one light year.

How it Works

The converter multiplies your value by fixed physical factors: 1 light year = 63,241.1 AU = 9.461 × 10¹² km, and 1 AU = 1.496 × 10⁸ km (the mean Earth-Sun distance). Equivalent reverse factors (1.5813 × 10^-5 ly per AU, plus 1.057 × 10^-13 ly and 6.685 × 10^-9 AU per km) are applied when converting from those units. Every result is shown in scientific notation with four decimal places, so both planetary and stellar scales stay readable.