Convert Megameter to Exameter
Convert megameters to exameters instantly. 1 megameter = 1e-12 exameter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Exameter to Megameter converter for the reverse conversion.
Units explained
Megameter
A megameter is a metric unit of length equal to one million meters (1×10⁶ m, or 1,000 km). It is occasionally used in geophysics and astronomy when expressing planetary-scale distances in SI units.
The megameter uses the SI prefix mega- (from Greek megas, great), adopted by the CGPM in 1960 to denote multiplication by one million.
Megameters appear in geophysics (Earth's mean radius is 6.371 Mm), planetary science, and large-scale civil engineering planning. The unit is less common than the kilometer for everyday geographic distances.
SI prefix mega- adopted in 1960; the megameter is the standard SI prefix unit for distances comparable to planetary radii.
Exameter
An exameter is a metric unit of length equal to one quintillion meters (1×10¹⁸ m). It is among the largest defined SI prefix units of length and appears almost exclusively in astrophysical contexts.
The exameter uses the SI prefix exa- (from Greek hex, six, related to the exponent's powers-of-thousand grouping), adopted by the CGPM in 1975 to denote 10¹⁸.
Exameters could be used to express galactic-scale distances. One kiloparsec is approximately 30.9 Em. Astronomy generally uses parsecs, kiloparsecs, and megaparsecs instead.
SI prefix exa- adopted in 1975; the exameter has very limited practical use because galactic-scale astronomy has its own well-established unit system.
Megameter to Exameter conversion formula
The relationship between megameters and exameters:
To convert megameters to exameters, multiply the value in megameters by 1e-12. To reverse, multiply exameters by 1e+12.
How to use this converter
Type a value into the calculator. The result in exameters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Exameter to Megameter converter for the reverse direction.
Step-by-step: convert megameters to exameters
- Write down the value in megameters (Mm).
- Multiply that value by the factor 1e-12.
- The product is the equivalent value in exameters (Em).
- To reverse, multiply the exameter value by 1e+12.
Worked examples
Example 1 — Convert 1 Mm to Em:
1 × 1e-12 = 1e-12 Em
Example 2 — Convert 100 Mm to Em:
100 × 1e-12 = 1e-10 Em
Megameter to Exameter conversion table
Standard reference values for converting megameters to exameters:
| Megameter [Mm] | Exameter [Em] |
|---|---|
| 0.01 | 1e-14 |
| 0.1 | 1e-13 |
| 1 | 1e-12 |
| 2 | 2e-12 |
| 3 | 3e-12 |
| 4 | 4e-12 |
| 5 | 5e-12 |
| 10 | 1e-11 |
| 20 | 2e-11 |
| 30 | 3e-11 |
| 40 | 4e-11 |
| 50 | 5e-11 |
| 100 | 1e-10 |
| 500 | 5e-10 |
| 1000 | 1e-9 |
Frequently asked questions
How many exameters is 1 megameter?
How do I convert megameters to exameters?
How do I convert exameters back to megameters?
How many exameters is 100 megameters?
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Sources & references
Conversion factor (1 Mm = 1e-12 Em) 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.