Millijoules to Gigajoules Converter
Enter the energy in millijoules below to convert it to gigajoules.
Convert Millijoules to Gigajoules
Enter a value in millijoules (mJ) to convert to gigajoules (GJ).
Millijoule to Gigajoule Conversion Table
Table showing various millijoule measurements converted to gigajoules. Click any preset value or arrow to load it into the converter.
| Millijoules (mJ) | Gigajoules (GJ) |
|---|---|
| 1 mJ | 1e-12 GJ |
| 10 mJ | 1e-11 GJ |
| 100 mJ | 1e-10 GJ |
| 1,000 mJ | 1e-9 GJ |
| 10,000 mJ | 0.00000001 GJ |
| 100,000 mJ | 0.0000001 GJ |
| 1,000,000 mJ | 0.000001 GJ |
| 5,000,000 mJ | 0.000005 GJ |
| 10,000,000 mJ | 0.00001 GJ |
| 25,400,000 mJ | 0.0000254 GJ |
How to Convert Millijoules to Gigajoules
To convert millijoules to gigajoules, multiply the energy by the following conversion ratio: 1e-12 gigajoules/millijoule.
Since one millijoule is equal to 1e-12 gigajoules, you can use this simple formula to convert:
The energy in gigajoules is equal to the energy in millijoules multiplied by 1e-12.
For example, here's how to convert 5 millijoules to gigajoules using the formula above.
How Many Gigajoules Are in a Millijoule?
There are 1e-12 gigajoules in a millijoule, which is why we use this value in the formula above.
Our millijoule to gigajoule calculator automatically converts your energy measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Millijoules and gigajoules are both units used to measure energy. Keep reading to learn more about each unit.
What Is a Millijoule?
A millijoule is a unit of energy equal to 1/1,000 of a joule (0.001 J). One-thousandth of a Joule. [1]
The millijoule is classified as a metric and SI-compatible unit of energy. Millijoules can be abbreviated as mJ; for example, 1 millijoule can be written as 1 mJ.
In the metric system, "milli" is the standard SI prefix for thousandths, or 10⁻³. This makes the millijoule (mJ) a convenient decimal multiple of the joule (J).
In practice, millijoules (mJ) are widely used across fine-tolerance laboratory, analytical, and micro-scale energy measurements within SI metric workflows, engineering documentation, and technical data sheets.
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. [2]
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.
When converting energy between millijoules (mJ) and gigajoules (GJ), keep full floating-point precision (1 mJ = 1e-12 GJ; 1 GJ = 1e+12 mJ) during intermediate calculations and round only the final gigajoule figure to match your instrument tolerance.
More Millijoule & Gigajoule Conversions
Need to calculate in the opposite direction? Use our gigajoules to millijoules calculator to switch your starting unit immediately. You can also explore related tools such as converting gigajoules to millijoules, converting joules to calories, or converting calories to joules.
Convert from Millijoules
Frequently Asked Questions
References
- [1]NIST CODATA StandardNIST CODATA (CODATA Energy & Thermodynamic Constants)·Energy Metrology Standard — Millijoules (mJ) to Gigajoules (GJ)
- [2]NIST SP 811 SpecificationNIST SP 811 (NIST SP 811 App. B.9 (Energy, Work & Heat))·Unit Specifications: Millijoule (mJ) & Gigajoule (GJ)
- [3]BIPM ReferenceBIPM (Derived SI Unit: Joule (J))·Conversion Factors & Mathematical Basis (mJ to GJ)