Joule to Millijoule Converter
Convert Joule (J) to Millijoule (mJ) instantly. 1 J = 1,000 mJ.
Energy Converter
27 units available
1 J = 1,000 mJ
Formula:
mJ = J × 1,000With your value: 1 J = 1,000 mJ
How big is that?
Everyday references on a logarithmic scale, all expressed in joule so you can sanity-check the result.
Other Joule to Millijoule conversions
Joule to Millijoule Conversion Table
| Joule (J) | Millijoule (mJ) |
|---|---|
| 0.5 | 500 |
| 1 | 1,000 |
| 2 | 2,000 |
| 5 | 5,000 |
| 10 | 10,000 |
| 15 | 15,000 |
| 20 | 20,000 |
| 25 | 25,000 |
| 50 | 50,000 |
| 100 | 100,000 |
| 250 | 250,000 |
| 500 | 500,000 |
| 1000 | 1,000,000 |
Millijoule to Joule Conversion Table
| Millijoule (mJ) | Joule (J) |
|---|---|
| 0.5 | 0.0005 |
| 1 | 0.001 |
| 2 | 0.002 |
| 5 | 0.005 |
| 10 | 0.01 |
| 15 | 0.015 |
| 20 | 0.02 |
| 25 | 0.025 |
| 50 | 0.05 |
| 100 | 0.1 |
| 250 | 0.25 |
| 500 | 0.5 |
| 1000 | 1 |
Where these values come from
Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.
Joule (J)
Energy
Derived from the joule (1 J = 1 kg·m²/s²). Thermochemical and IT calories, BTU and kWh are exact defined multiples.
Source: NIST Special Publication 811, Guide for the Use of the International System of Units
National Institute of Standards and Technology (US) · Reviewed 2026-07-01
Millijoule (mJ)
Energy
Derived from the joule (1 J = 1 kg·m²/s²). Thermochemical and IT calories, BTU and kWh are exact defined multiples.
Source: NIST Special Publication 811, Guide for the Use of the International System of Units
National Institute of Standards and Technology (US) · Reviewed 2026-07-01
How to Convert Joule to Millijoule
To convert from Joule (J) to Millijoule (mJ), multiply the value by 1,000.
Formula: mJ = J × 1,000
Reverse: J = mJ × 0.001
Step-by-Step Example
- Start with your value in Joule. For example: 5 J
- Multiply by the conversion factor: 5 x 1,000
- The result is: 5,000 mJ
About Joule
The joule is the SI unit of energy. One joule equals the work done when a force of one newton moves an object one meter.
Common uses: physics, electrical engineering, chemistry.
About Millijoule
The millijoule (mJ) is a unit of energy and work. One millijoule equals 0.001 joules. UnitConvertLab converts it against every other energy unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.
Common uses: energy calculations, engineering and science, education.
Frequently Asked Questions
How many Millijoule are in 1 Joule?
There are exactly 1,000 Millijoule in 1 Joule. This means the conversion factor from Joule to Millijoule is 1,000.
What is the formula to convert Joule to Millijoule?
The formula to convert Joule to Millijoule is: mJ = J × 1,000. For example, to convert 10 Joule to Millijoule, you would multiply 10 by 1,000.
What is a Joule?
The joule is the SI unit of energy. One joule equals the work done when a force of one newton moves an object one meter.
What is a Millijoule?
The millijoule (mJ) is a unit of energy and work. One millijoule equals 0.001 joules. UnitConvertLab converts it against every other energy unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.
What are the common uses of Joule?
The Joule is commonly used in physics, electrical engineering, chemistry.
Related Energy Conversions
Cite this page
UnitConvertLab. (2026). Joule to Millijoule converter. UnitConvertLab. Retrieved from https://unitconvertlab.com/convert/joule-to-millijoule