Gigajoules to Megajoules Converter
Enter the energy in gigajoules below to convert it to megajoules.
Convert Gigajoules to Megajoules
Enter a value in gigajoules (GJ) to convert to megajoules (MJ).
Gigajoule to Megajoule Conversion Table
Table showing various gigajoule measurements converted to megajoules. Click any preset value or arrow to load it into the converter.
How to Convert Gigajoules to Megajoules
To convert gigajoules to megajoules, multiply the energy by the following conversion ratio: 1,000 megajoules/gigajoule.
Since one gigajoule is equal to 1,000 megajoules, you can use this simple formula to convert:
The energy in megajoules is equal to the energy in gigajoules multiplied by 1,000.
For example, here's how to convert 5 gigajoules to megajoules using the formula above.
How Many Megajoules Are in a Gigajoule?
There are 1,000 megajoules in a gigajoule, which is why we use this value in the formula above.
Our gigajoule to megajoule calculator automatically converts your energy measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Gigajoules and megajoules are both units used to measure energy. Keep reading to learn more about each unit.
What Is a Gigajoule?
A gigajoule is a unit of energy equal to 1,000,000,000 joules (J), the base unit for energy. Equal to 1,000,000,000 Joules, common in natural gas billing. [1]
The gigajoule is classified as an International System of Units (SI) unit of energy. Gigajoules can be abbreviated as GJ; for example, 1 gigajoule can be written as 1 GJ.
In the metric system, "giga" is the standard SI prefix for billions, or 10⁹. This makes the gigajoule (GJ) a convenient decimal multiple of the joule (J).
In practice, gigajoules (GJ) are widely used across large-scale industrial, bulk, and macro-level energy specifications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.
What Is a Megajoule?
A megajoule is a unit of energy equal to 1,000,000 joules (J), the base unit for energy. Equal to 1,000,000 Joules. [2]
The megajoule is classified as an International System of Units (SI) unit of energy. Megajoules can be abbreviated as MJ; for example, 1 megajoule can be written as 1 MJ.
In the metric system, "mega" is the standard SI prefix for millions, or 10⁶. This makes the megajoule (MJ) a convenient decimal multiple of the joule (J).
In practice, megajoules (MJ) are widely used across large-scale industrial, bulk, and macro-level energy specifications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.
When converting energy between gigajoules (GJ) and megajoules (MJ), keep full floating-point precision (1 GJ = 1,000 MJ; 1 MJ = 0.001 GJ) during intermediate calculations and round only the final megajoule figure to match your instrument tolerance.
More Gigajoule & Megajoule Conversions
Need to calculate in the opposite direction? Use our megajoules to gigajoules calculator to switch your starting unit immediately. You can also explore related tools such as converting megajoules to gigajoules, converting joules to calories, or converting calories to joules.
Convert from Gigajoules
Frequently Asked Questions
References
- [1]NIST CODATA StandardNIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Gigajoules (GJ) to Megajoules (MJ)
- [2]NIST SP 811 SpecificationNIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Gigajoule (GJ) & Megajoule (MJ)
- [3]BIPM ReferenceBIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (GJ to MJ)