Convert Megameter to Decimeter
Convert megameters to decimeters instantly. 1 megameter = 1e+7 decimeter — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Decimeter 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.
Decimeter
A decimeter is a metric unit of length equal to one tenth of a meter (1/10 m). Though uncommon in English-speaking countries, it remains a standard SI unit and is used in some scientific and educational contexts.
Like the centimeter and millimeter, the decimeter was defined when France adopted the metric system in 1795, using the SI prefix deci- (from Latin decimus, "tenth").
Decimeters are rarely used in everyday measurement in English-speaking countries but appear in some European technical specifications and in volume conversions (1 cubic decimeter = 1 liter).
Defined in 1795 as part of the original French metric system; remains a recognized SI unit though uncommonly used in commerce.
Megameter to Decimeter conversion formula
The relationship between megameters and decimeters:
To convert megameters to decimeters, multiply the value in megameters by 1e+7. To reverse, multiply decimeters by 1e-7.
How to use this converter
Type a value into the calculator. The result in decimeters updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Decimeter to Megameter converter for the reverse direction.
Step-by-step: convert megameters to decimeters
- Write down the value in megameters (Mm).
- Multiply that value by the factor 1e+7.
- The product is the equivalent value in decimeters (dm).
- To reverse, multiply the decimeter value by 1e-7.
Worked examples
Example 1 — Convert 1 Mm to dm:
1 × 1e+7 = 1e+7 dm
Example 2 — Convert 100 Mm to dm:
100 × 1e+7 = 1e+9 dm
Megameter to Decimeter conversion table
Standard reference values for converting megameters to decimeters:
| Megameter [Mm] | Decimeter [dm] |
|---|---|
| 0.01 | 100000 |
| 0.1 | 1000000 |
| 1 | 1e+7 |
| 2 | 2e+7 |
| 3 | 3e+7 |
| 4 | 4e+7 |
| 5 | 5e+7 |
| 10 | 1e+8 |
| 20 | 2e+8 |
| 30 | 3e+8 |
| 40 | 4e+8 |
| 50 | 5e+8 |
| 100 | 1e+9 |
| 500 | 5e+9 |
| 1000 | 1e+10 |
Frequently asked questions
How many decimeters is 1 megameter?
How do I convert megameters to decimeters?
How do I convert decimeters back to megameters?
How many decimeters is 100 megameters?
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Sources & references
Conversion factor (1 Mm = 1e+7 dm) 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.