Convert Gigameter to Megameter
Convert gigameters to megameters instantly. 1 gigameter = 1000 megameter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Megameter to Gigameter converter for the reverse conversion.
Units explained
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
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 to Megameter conversion formula
The relationship between gigameters and megameters:
To convert gigameters to megameters, multiply the value in gigameters by 1000. To reverse, multiply megameters by 0.001.
How to use this converter
Type a value into the calculator. The result in megameters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Megameter to Gigameter converter for the reverse direction.
Step-by-step: convert gigameters to megameters
- Write down the value in gigameters (Gm).
- Multiply that value by the factor 1000.
- The product is the equivalent value in megameters (Mm).
- To reverse, multiply the megameter value by 0.001.
Worked examples
Example 1 — Convert 1 Gm to Mm:
1 × 1000 = 1000 Mm
Example 2 — Convert 100 Gm to Mm:
100 × 1000 = 100000 Mm
Gigameter to Megameter conversion table
Standard reference values for converting gigameters to megameters:
| Gigameter [Gm] | Megameter [Mm] |
|---|---|
| 0.01 | 10 |
| 0.1 | 100 |
| 1 | 1000 |
| 2 | 2000 |
| 3 | 3000 |
| 4 | 4000 |
| 5 | 5000 |
| 10 | 10000 |
| 20 | 20000 |
| 30 | 30000 |
| 40 | 40000 |
| 50 | 50000 |
| 100 | 100000 |
| 500 | 500000 |
| 1000 | 1000000 |
Frequently asked questions
How many megameters is 1 gigameter?
How do I convert gigameters to megameters?
How do I convert megameters back to gigameters?
How many megameters is 100 gigameters?
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Sources & references
Conversion factor (1 Gm = 1000 Mm) 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.