Convert Kilometer to Megaparsec
Convert kilometers to megaparsecs instantly. 1 kilometer = 3.240779e-20 megaparsec — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Megaparsec to Kilometer converter for the reverse conversion.
Units explained
Kilometer
A kilometer is a metric unit of length equal to one thousand meters. It is the standard unit for measuring road distances, geographic distances, and other large-scale measurements in metric countries.
The kilometer was defined alongside the meter in 1795 using the standard SI prefix kilo- (from Greek chilioi, "thousand"), denoting one thousand units.
Kilometers are used worldwide (except the United States and a few others) for road signage, geographic distance, athletic events, and scientific distances at planetary scale. Speed limits in most countries are given in km/h.
Adopted 1795 in France as part of the original metric system; the kilometer became the global standard for road and geographic distance through the 19th and 20th century metric adoption.
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.
Kilometer to Megaparsec conversion formula
The relationship between kilometers and megaparsecs:
To convert kilometers to megaparsecs, multiply the value in kilometers by 3.240779e-20. To reverse, multiply megaparsecs by 3.085678e+19.
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 Kilometer converter for the reverse direction.
Step-by-step: convert kilometers to megaparsecs
- Write down the value in kilometers (km).
- Multiply that value by the factor 3.240779e-20.
- The product is the equivalent value in megaparsecs (Mpc).
- To reverse, multiply the megaparsec value by 3.085678e+19.
Worked examples
Example 1 — Convert 1 km to Mpc:
1 × 3.240779e-20 = 3.240779e-20 Mpc
Example 2 — Convert 100 km to Mpc:
100 × 3.240779e-20 = 3.240779e-18 Mpc
Real-world example — Maritime exclusion zone
A 200-kilometer exclusion zone (a common maritime boundary) converts to a different value in megaparsecs that's useful when describing the same zone in everyday land-distance units.
200 km × 3.240779e-20 = 6.481559e-18 Mpc
Real-world example — Coastal cruise distances
A 10-kilometer coastal sailing route converts to a different value in megaparsecs — useful for cruise operators who switch between maritime, aviation, and road-distance units depending on the leg of the trip.
10 km × 3.240779e-20 = 3.240779e-19 Mpc
Real-world example — Road-sign distances across systems
A 100-kilometer road sign converts cleanly into megaparsecs — exactly the conversion drivers planning trips abroad rely on when reading road signs in a different measurement system.
100 km × 3.240779e-20 = 3.240779e-18 Mpc
Kilometer to Megaparsec conversion table
Standard reference values for converting kilometers to megaparsecs:
| Kilometer [km] | Megaparsec [Mpc] |
|---|---|
| 0.01 | 3.240779e-22 |
| 0.1 | 3.240779e-21 |
| 1 | 3.240779e-20 |
| 2 | 6.481559e-20 |
| 3 | 9.722338e-20 |
| 4 | 1.296312e-19 |
| 5 | 1.62039e-19 |
| 10 | 3.240779e-19 |
| 20 | 6.481559e-19 |
| 30 | 9.722338e-19 |
| 40 | 1.296312e-18 |
| 50 | 1.62039e-18 |
| 100 | 3.240779e-18 |
| 500 | 1.62039e-17 |
| 1000 | 3.240779e-17 |
Frequently asked questions
How many megaparsecs is 1 kilometer?
How do I convert kilometers to megaparsecs?
How do I convert megaparsecs back to kilometers?
How many megaparsecs is 100 kilometers?
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Sources & references
Conversion factor (1 km = 3.240779e-20 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.