Microjoule is 0.000001 joule units.
Microjoules to Joules Converter — uJ to J
Convert Microjoule (uJ) to Joule (J) using the exact conversion factor (1 microjoule = 0.000001 joule). See the formula, worked examples, conversion table, history, and common uses.
Microjoules to Joules 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.
The joule is the SI derived unit of energy.
Result = input x 1e-6 / 1.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Microjoules to Joules
Microjoule and Joule both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Specifically: Microjoule is 0.000001 joule units, and the joule is the SI derived unit of energy.
Formula
joules = microjoules × 0.000001
This factor comes from each unit's defined relationship to the category's base unit: 1 microjoule equals 0.000001 base units, and 1 joule equals 1 base unit, so dividing one by the other gives the direct microjoule-to-joule factor of 0.000001.
Simple example
1 uJ × 0.000001 = 0.000001 J
1 microjoule = 0.000001 joules.
Real-world example
100 uJ × 0.000001 = 0.0001 J
100 microjoules = 0.0001 joules.
Conversion table
| Microjoule (uJ) | Joule (J) |
|---|---|
| 1 uJ | 0.000001 J |
| 10 uJ | 0.00001 J |
| 100 uJ | 0.0001 J |
| 500 uJ | 0.0005 J |
| 1,000 uJ | 0.001 J |
| 2,000 uJ | 0.002 J |
Reverse conversion: Joule to Microjoule
0.000001 J × 1000000 = 1 uJ
0.000001 joules = 1 microjoule.
microjoules = joules × 1000000
For a page dedicated to this direction, see Joule to Microjoule.
Understanding the Microjoule (uJ)
Microjoule is 0.000001 joule units.
Understanding the Joule
Joule (J) measures energy. The joule is the SI derived unit of energy, defined as the work done by one newton acting over one meter. It is classified as a SI derived unit.
Where it's used: Standard scientific and engineering energy unit worldwide
Uses of the Joule today
- Physics and engineering energy calculations
- Electrical energy in scientific contexts (though kWh is used for billing)
- Nutrition labeling in some countries (alongside or instead of calories)
History of the Joule
The joule is named after English physicist James Prescott Joule, whose experiments in the 1840s established the mechanical equivalent of heat — demonstrating that mechanical work and heat are interchangeable forms of energy, foundational to the first law of thermodynamics.
The unit itself was formally adopted as the SI derived unit of energy by international agreement as part of the broader SI system, defined coherently from the base units (kg, m, s) rather than as an independent physical standard.
Historical origin. Joule was not the invention of a single named person; it developed through the process described above.
Joule — sources
- BIPM SI Brochure — Coherent derived units — Defines the joule as the SI unit of energy.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many joules are in 1 microjoule?
1 microjoule equals 0.000001 joules, using the exact defined conversion factor rather than an estimate.
How do I convert microjoule to joule?
Multiply the microjoule value by 0.000001. The converter above does this instantly to whatever precision you set.
How do I convert joule back to microjoule?
Use the reverse factor: 1 joule equals 1,000,000 microjoules. You can also use the swap control in the converter above to flip the direction instantly.
What is a microjoule?
Microjoule (uJ) is a unit of energy.
What is a joule?
Joule (J) measures energy. The joule is the SI derived unit of energy, defined as the work done by one newton acting over one meter. It is classified as a SI derived unit.
Is the microjoule to joule conversion exact?
Yes. Both microjoule and joule are defined by fixed standards rather than physical artifacts, so the factor of 0.000001 used above is exact to as many digits as you choose to display.