Light years to parsecs
Convert light years (ly) to parsecs (pc) with our converter. You get instant and precise results calculated from the definitions of both units.
1 ly = 0.306601 pc
Formula
If you want to convert light years to parsecs manually, use the formula below. This provides a quick approximation based on the standard astronomical relationship. For higher precision, the converter uses definition-based values computed at full numerical accuracy.
Conversion formula: pc = ly ÷ 3.261564
Scientific basis: This relationship follows from the physical definition of the light year (distance light travels in a vacuum in one Julian year) and the geometric definition of the parsec (stellar parallax geometry).
Equivalent value: 1 ly ≈ 0.30660139 pc
Example: 2 ly = 2 ÷ 3.261564 = 0.613203 pc
Scientific derivation:
1 ly = c × 31,557,600 s
c = 299,792,458 m/s
1 pc = 1 AU ÷ tan(1″)
1 AU = 149,597,870,700 m
1″ = π / (180 × 3600) radians
Combining these definitions gives a definition-based conversion at full numerical precision.
Explanation: To convert light years to parsecs, divide by 3.261564 for quick manual calculations.
Table
| Light years (ly) | Parsecs (pc) |
|---|---|
| 1 ly | 0.306601 pc |
| 2 ly | 0.613203 pc |
| 3 ly | 0.919804 pc |
| 4 ly | 1.226406 pc |
| 5 ly | 1.533007 pc |
| 10 ly | 3.066014 pc |
| 25 ly | 7.665035 pc |
| 50 ly | 15.330070 pc |
| 75 ly | 22.995105 pc |
| 100 ly | 30.660139 pc |
| 1,000 ly | 306.601394 pc |
FAQ
What is a light year?
A light year (ly) is the distance light travels in a vacuum in one Julian year (365.25 days). Astronomers use it to express distances between stars, galaxies, and other large-scale structures. Despite its name, it measures distance, not time.
What is a parsec?
A parsec (pc) is a unit of distance defined geometrically as the distance at which one astronomical unit (AU) subtends an angle of one arcsecond. It follows directly from stellar parallax measurements and is widely used for distance estimation in astronomy.
How many parsecs is 1 light year?
1 light year equals approximately 0.306601 parsecs. This value follows from the inverse of the parsec-to-light-year relationship and is typically rounded for readability.
Why do astronomers use parsecs?
Astronomers use parsecs because the unit links directly to stellar parallax, which relates observed angular shifts to distance. This makes parsecs especially practical for calculating distances from observational data.
How do you convert light years to parsecs?
Divide the number of light years by 3.261564 to convert to parsecs. This factor is a rounded decimal form of the exact relationship defined by the light year and the parsec.
Example: 10 ly ÷ 3.261564 = 3.066014 pc