Convert Megaparsec to Light Year
Convert megaparsecs to light years instantly. 1 megaparsec = 3261563.7771674334 light year — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Light Year to Megaparsec converter for the reverse conversion.
Units explained
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
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 to Light Year conversion formula
The relationship between megaparsecs and light years:
To convert megaparsecs to light years, multiply the value in megaparsecs by 3261563.7771674334. To reverse, multiply light years by 3.066014e-7.
How to use this converter
Type a value into the calculator. The result in light years updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Light Year to Megaparsec converter for the reverse direction.
Step-by-step: convert megaparsecs to light years
- Write down the value in megaparsecs (Mpc).
- Multiply that value by the factor 3261563.7771674334.
- The product is the equivalent value in light years (ly).
- To reverse, multiply the light year value by 3.066014e-7.
Worked examples
Example 1 — Convert 1 Mpc to ly:
1 × 3261563.7771674334 = 3261563.7771674334 ly
Example 2 — Convert 100 Mpc to ly:
100 × 3261563.7771674334 = 3.261564e+8 ly
Megaparsec to Light Year conversion table
Standard reference values for converting megaparsecs to light years:
| Megaparsec [Mpc] | Light Year [ly] |
|---|---|
| 0.01 | 32615.6377716743 |
| 0.1 | 326156.3777167434 |
| 1 | 3261563.7771674334 |
| 2 | 6523127.5543348668 |
| 3 | 9784691.3315022998 |
| 4 | 1.304626e+7 |
| 5 | 1.630782e+7 |
| 10 | 3.261564e+7 |
| 20 | 6.523128e+7 |
| 30 | 9.784691e+7 |
| 40 | 1.304626e+8 |
| 50 | 1.630782e+8 |
| 100 | 3.261564e+8 |
| 500 | 1.630782e+9 |
| 1000 | 3.261564e+9 |
Frequently asked questions
How many light years is 1 megaparsec?
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Popular length unit conversions
Convert Megaparsec to other length units
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Metric / SI (4 units)
Imperial / US Customary (4 units)
Astronomical (8 units)
Sources & references
Conversion factor (1 Mpc = 3261563.7771674334 ly) 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.