Convert Light Year to Megaparsec
Convert light years to megaparsecs instantly. 1 light year = 3.066014e-7 megaparsec — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Megaparsec to Light Year converter for the reverse conversion.
Units explained
Light Year
A light year is the distance light travels in one Julian year in vacuum — exactly 9,460,730,472,580,800 meters (about 9.46×10¹⁵ m). It is the most common unit for expressing inter-stellar distances in non-technical astronomy.
Defined as the speed of light (299,792,458 m/s, exact) multiplied by one Julian year (365.25 days × 86400 seconds/day). Both factors are exact, making the light year exact by definition.
Light years are used in popular astronomy, science journalism, and stellar distance descriptions. The nearest star (Proxima Centauri) is 4.24 ly away; the Milky Way is about 100,000 ly across.
Concept of distance-as-time used since the 19th century; the modern exact definition follows from the 1983 SI definition of the meter via the speed of light.
Megaparsec
A megaparsec is a distance unit equal to one million parsecs (about 3.09×10²² m). It is the standard unit for cosmological-scale distances.
Combines the metric-style prefix mega- with the parsec. Standardised in astronomy for inter-galactic distances and cosmological calculations.
Megaparsecs are used in cosmology to express distances to other galaxies (Andromeda is ~0.78 Mpc), galaxy-cluster separations, and the Hubble constant (typically quoted as ~70 km/s per Mpc).
Exact via the parsec; the megaparsec is the standard scale unit in modern cosmology.
Light Year to Megaparsec conversion formula
The relationship between light years and megaparsecs:
To convert light years to megaparsecs, multiply the value in light years by 3.066014e-7. To reverse, multiply megaparsecs by 3261563.7771674334.
How to use this converter
Type a value into the calculator. The result in megaparsecs updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Megaparsec to Light Year converter for the reverse direction.
Step-by-step: convert light years to megaparsecs
- Write down the value in light years (ly).
- Multiply that value by the factor 3.066014e-7.
- The product is the equivalent value in megaparsecs (Mpc).
- To reverse, multiply the megaparsec value by 3261563.7771674334.
Worked examples
Example 1 — Convert 1 ly to Mpc:
1 × 3.066014e-7 = 3.066014e-7 Mpc
Example 2 — Convert 100 ly to Mpc:
100 × 3.066014e-7 = 3.066014e-5 Mpc
Light Year to Megaparsec conversion table
Standard reference values for converting light years to megaparsecs:
| Light Year [ly] | Megaparsec [Mpc] |
|---|---|
| 0.01 | 3.066014e-9 |
| 0.1 | 3.066014e-8 |
| 1 | 3.066014e-7 |
| 2 | 6.132028e-7 |
| 3 | 9.198042e-7 |
| 4 | 1.226406e-6 |
| 5 | 1.533007e-6 |
| 10 | 3.066014e-6 |
| 20 | 6.132028e-6 |
| 30 | 9.198042e-6 |
| 40 | 1.226406e-5 |
| 50 | 1.533007e-5 |
| 100 | 3.066014e-5 |
| 500 | 0.0001533007 |
| 1000 | 0.0003066014 |
Frequently asked questions
How many megaparsecs is 1 light year?
How do I convert light years to megaparsecs?
How do I convert megaparsecs back to light years?
How many megaparsecs is 100 light years?
Popular length unit conversions
Convert Light Year to other length units
Show all Light Year conversions
Metric / SI (4 units)
Imperial / US Customary (4 units)
Astronomical (8 units)
Sources & references
Conversion factor (1 ly = 3.066014e-7 Mpc) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Astronomical Union — System of Astronomical Constants
The IAU defines astronomical units including the AU (149597870700 m exactly) light-year and parsec used in astronomy and astrophysics.