Gigajoule is 1000000000 joule units.
Gigajoules to Megajoules Converter — GJ to MJ
Convert Gigajoule (GJ) to Megajoule (MJ) using the exact conversion factor (1 gigajoule = 1,000 megajoule). See the formula, worked examples, and conversion table.
Gigajoules to Megajoules converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
Megajoule is 1000000 joule units.
Result = input x 1e+9 / 1e+6.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Gigajoules to Megajoules
Gigajoule and Megajoule both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. Specifically: Gigajoule is 1000000000 joule units, and megajoule is 1000000 joule units.
Formula
megajoules = gigajoules × 1000
This factor comes from each unit's defined relationship to the category's base unit: 1 gigajoule equals 1000000000 base units, and 1 megajoule equals 1000000 base units, so dividing one by the other gives the direct gigajoule-to-megajoule factor of 1000.
Simple example
1 GJ × 1000 = 1,000 MJ
1 gigajoule = 1,000 megajoules.
Real-world example
100 GJ × 1000 = 100,000 MJ
100 gigajoules = 100,000 megajoules.
Conversion table
| Gigajoule (GJ) | Megajoule (MJ) |
|---|---|
| 1 GJ | 1,000 MJ |
| 10 GJ | 10,000 MJ |
| 50 GJ | 50,000 MJ |
| 100 GJ | 100,000 MJ |
| 500 GJ | 500,000 MJ |
| 1,000 GJ | 1,000,000 MJ |
Reverse conversion: Megajoule to Gigajoule
1 MJ × 0.001 = 0.001 GJ
1 megajoule = 0.001 gigajoules.
gigajoules = megajoules × 0.001
For a page dedicated to this direction, see Megajoule to Gigajoule.
Understanding the Gigajoule (GJ)
Gigajoule is 1000000000 joule units.
Understanding the Megajoule (MJ)
Megajoule is 1000000 joule units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many megajoules are in 1 gigajoule?
1 gigajoule equals 1,000 megajoules, using the exact defined conversion factor rather than an estimate.
How do I convert gigajoule to megajoule?
Multiply the gigajoule value by 1000. The converter above does this instantly to whatever precision you set.
How do I convert megajoule back to gigajoule?
Use the reverse factor: 1 megajoule equals 0.001 gigajoules. You can also use the swap control in the converter above to flip the direction instantly.
What is a gigajoule?
Gigajoule (GJ) is a unit of engineering.
What is a megajoule?
Megajoule (MJ) is a unit of engineering.
Is the gigajoule to megajoule conversion exact?
Yes. Both gigajoule and megajoule are defined by fixed standards rather than physical artifacts, so the factor of 1000 used above is exact to as many digits as you choose to display.
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.