Megajoule is 1000000 joule units.
Megajoules to Gigajoules Converter — MJ to GJ
Convert Megajoule (MJ) to Gigajoule (GJ) using the exact conversion factor (1 megajoule = 0.001 gigajoule). See the formula, worked examples, and conversion table.
Megajoules to Gigajoules converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
Gigajoule is 1000000000 joule units.
Result = input x 1e+6 / 1e+9.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Megajoules to Gigajoules
Megajoule and Gigajoule both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Specifically: Megajoule is 1000000 joule units, and gigajoule is 1000000000 joule units.
Formula
gigajoules = megajoules × 0.001
This factor comes from each unit's defined relationship to the category's base unit: 1 megajoule equals 1000000 base units, and 1 gigajoule equals 1000000000 base units, so dividing one by the other gives the direct megajoule-to-gigajoule factor of 0.001.
Simple example
1 MJ × 0.001 = 0.001 GJ
1 megajoule = 0.001 gigajoules.
Real-world example
100 MJ × 0.001 = 0.1 GJ
100 megajoules = 0.1 gigajoules.
Conversion table
| Megajoule (MJ) | Gigajoule (GJ) |
|---|---|
| 1 MJ | 0.001 GJ |
| 10 MJ | 0.01 GJ |
| 100 MJ | 0.1 GJ |
| 500 MJ | 0.5 GJ |
| 1,000 MJ | 1 GJ |
| 2,000 MJ | 2 GJ |
Reverse conversion: Gigajoule to Megajoule
0.001 GJ × 1000 = 1 MJ
0.001 gigajoules = 1 megajoule.
megajoules = gigajoules × 1000
For a page dedicated to this direction, see Gigajoule to Megajoule.
Understanding the Megajoule (MJ)
Megajoule is 1000000 joule units.
Understanding the Gigajoule (GJ)
Gigajoule is 1000000000 joule units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many gigajoules are in 1 megajoule?
1 megajoule equals 0.001 gigajoules, using the exact defined conversion factor rather than an estimate.
How do I convert megajoule to gigajoule?
Multiply the megajoule value by 0.001. The converter above does this instantly to whatever precision you set.
How do I convert gigajoule back to megajoule?
Use the reverse factor: 1 gigajoule equals 1,000 megajoules. You can also use the swap control in the converter above to flip the direction instantly.
What is a megajoule?
Megajoule (MJ) is a unit of energy.
What is a gigajoule?
Gigajoule (GJ) is a unit of energy.
Is the megajoule to gigajoule conversion exact?
Yes. Both megajoule and gigajoule are defined by fixed standards rather than physical artifacts, so the factor of 0.001 used above is exact to as many digits as you choose to display.