Light years to Parsecs Converter

How many parsecs are in a light year?

One light year equals about 0.306601 parsec. Put the other way, one parsec is about 3.2616 light years. The converter divides your light years by 3.261563 to get parsecs.

parsecs = light years ÷ 3.261563Equivalent to multiplying by 0.306601.

The tool uses 3.261563 ly per parsec. A more precise value is 3.2615638, so the two differ by roughly 2 × 10^-7 in relative terms, far below anything you could notice in a result.

Two different ways to measure the sky

A light year is a distance defined by travel time. It is how far light moves in a vacuum during one Julian year of 365.25 days, which works out to exactly 9,460,730,472,580,800 meters, or roughly 9.46 trillion kilometers. It is easy to picture, and it is the unit used in news and popular science.

A parsec comes from geometry. As the Earth circles the Sun, a nearby star appears to shift slightly against distant background stars. The parsec is the distance at which one astronomical unit (the Earth-Sun distance) spans an angle of one arcsecond. That makes it about 3.0857 × 10¹⁶ meters, or around 206,265 astronomical units. Professional astronomers prefer it because a measured parallax angle converts directly into a distance in parsecs.

For larger scales the parsec takes metric prefixes: a kiloparsec (kpc) is 1,000 pc and a megaparsec (Mpc) is 1,000,000 pc.

How to convert light years to parsecs

1. Type the distance in light years into the first box.
2. Read the distance in parsecs from the second box. It updates as you type.
3. To check by hand, divide by 3.261563 or multiply by 0.306601.

Example 1. Proxima Centauri, the closest known star to the Sun, is about 4.25 ly away. 4.25 ÷ 3.261563 ≈ 1.3031 pc.

Example 2. The Milky Way's bright disc is often quoted as roughly 100,000 ly across. 100,000 ÷ 3.261563 ≈ 30,660.15 pc, or about 30.7 kpc.

Example 3. The Andromeda Galaxy lies at roughly 2.5 million ly. 2,500,000 ÷ 3.261563 ≈ 766,503.67 pc, which is about 0.77 Mpc.

Light years to parsecs conversion table

Notes on accuracy

The conversion itself is a fixed ratio, but the distances you plug in are not always precise. Distances to remote galaxies are estimates that get revised as measurements improve, so a result like 766,503.67 pc should be read as "about 0.77 Mpc".

The reverse calculation is on the parsecs to light years converter. For everyday speeds and lengths on Earth, browse the physics converters and the distance converters.