Unit Converters · Astronomical
Astronomical Distance Converter
Convert astronomical distances between kilometres, miles, light-seconds to light-years, astronomical units and parsecs (up to megaparsecs), using the International Astronomical Union's exact definitions.
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1 Light-year =
9,460,730,473,000 Kilometers
1 Light-year = 9,460,730,473,000 Kilometers
- Miles
- 5,878,625,373,000
- Light-seconds
- 31,557,600
- Light-minutes
- 525,960
- Light-hours
- 8,766
- Astronomical Units
- 63,241.07708
- Parsecs
- 0.3066013938
- Kiloparsecs
- 0.0003066013938
- Megaparsecs
- 3.066013938 × 10⁻⁷
How this is calculated
1 AU = 149,597,870,700 m · 1 ly = 299,792,458 m/s × 365.25 days = 9,460,730,472,580,800 m · 1 pc = 648,000/π AU
- AU
- Astronomical unit — roughly the Earth–Sun distance, fixed exactly by the IAU in 2012
- pc
- Parsec — the distance at which 1 AU subtends one arcsecond (≈ 3.26 light-years)
Astronomers use units scaled to the distances they measure: astronomical units within the Solar System, light-years and parsecs between stars, and megaparsecs between galaxies. All of them are defined exactly in metres, so conversions are exact; results show 10 significant figures.
Assumptions & sources
- Light-year uses the Julian year (365.25 days) as defined by the IAU.
- 1IAU 2012 Resolution B2 — re-definition of the astronomical unit — International Astronomical Union
- 2The International System of Units (SI Brochure) — non-SI units accepted for use — BIPM
Calculator ID UNIT-ASTRO-001 · version 1.0.0
Common questions
How far is a light-year?
About 9.46 trillion km — the distance light travels in a Julian year of 365.25 days.
Is a parsec a unit of time?
No, it's a distance: about 3.26 light-years. It comes from 'parallax of one arcsecond'.