Convert Megameter to Gigameter
Convert megameters to gigameters instantly. 1 megameter = 0.001 gigameter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Gigameter 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.
Gigameter
A gigameter is a metric unit of length equal to one billion meters (1×10⁹ m). It is most often used in astronomy and astrophysics when expressing distances within the inner solar system.
The gigameter uses the SI prefix giga- (from Greek gigas, giant), adopted by the CGPM in 1960 to denote multiplication by one billion (10⁹).
Gigameters are used to express distances such as the Sun's diameter (~1.39 Gm), the Earth–Moon distance (~0.384 Gm), and similar inner-solar-system scales. Astronomical units and light-seconds are also common for these distances.
SI prefix giga- adopted in 1960; the gigameter became standard in astronomy for sub-AU distances by the late 20th century.
Megameter to Gigameter conversion formula
The relationship between megameters and gigameters:
To convert megameters to gigameters, multiply the value in megameters by 0.001. To reverse, multiply gigameters by 1000.
How to use this converter
Type a value into the calculator. The result in gigameters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Gigameter to Megameter converter for the reverse direction.
Step-by-step: convert megameters to gigameters
- Write down the value in megameters (Mm).
- Multiply that value by the factor 0.001.
- The product is the equivalent value in gigameters (Gm).
- To reverse, multiply the gigameter value by 1000.
Worked examples
Example 1 — Convert 1 Mm to Gm:
1 × 0.001 = 0.001 Gm
Example 2 — Convert 100 Mm to Gm:
100 × 0.001 = 0.1 Gm
Megameter to Gigameter conversion table
Standard reference values for converting megameters to gigameters:
| Megameter [Mm] | Gigameter [Gm] |
|---|---|
| 0.01 | 1e-5 |
| 0.1 | 0.0001 |
| 1 | 0.001 |
| 2 | 0.002 |
| 3 | 0.003 |
| 4 | 0.004 |
| 5 | 0.005 |
| 10 | 0.01 |
| 20 | 0.02 |
| 30 | 0.03 |
| 40 | 0.04 |
| 50 | 0.05 |
| 100 | 0.1 |
| 500 | 0.5 |
| 1000 | 1 |
Frequently asked questions
How many gigameters is 1 megameter?
How do I convert megameters to gigameters?
How do I convert gigameters back to megameters?
How many gigameters is 100 megameters?
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Sources & references
Conversion factor (1 Mm = 0.001 Gm) 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 Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.