An electronvolt is the energy gained by an electron across one volt.
Electronvolts to Joules Converter — eV to J
Convert Electronvolt (eV) to Joule (J) using the exact conversion factor (1 electronvolt = 1.602177e-19 joule). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Electronvolts 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 1.60217663e-19 / 1.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Electronvolts to Joules
Electronvolt and Joule both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Electronvolt is typically associated with standard unit throughout particle physics, atomic physics, and chemistry worldwide, while Joule is typically associated with standard scientific and engineering energy unit worldwide.
Formula
joules = electronvolts × 1.602177e-19
This factor comes from each unit's defined relationship to the category's base unit: 1 electronvolt equals 1.602177e-19 base units, and 1 joule equals 1 base unit, so dividing one by the other gives the direct electronvolt-to-joule factor of 1.602177e-19.
Simple example
1 eV × 1.602177e-19 = 1.602177e-19 J
1 electronvolt = 1.602177e-19 joules.
Real-world example
100 eV × 1.602177e-19 = 1.602177e-17 J
100 electronvolts = 1.602177e-17 joules.
Conversion table
| Electronvolt (eV) | Joule (J) |
|---|---|
| 1 eV | 1.602177e-19 J |
| 10 eV | 1.602177e-18 J |
| 100 eV | 1.602177e-17 J |
| 500 eV | 8.010883e-17 J |
| 1,000 eV | 1.602177e-16 J |
| 2,000 eV | 3.204353e-16 J |
Reverse conversion: Joule to Electronvolt
1.602177e-19 J × 6.241509e+18 = 1.000000228 eV
1.602177e-19 joules = 1.000000228 electronvolts.
electronvolts = joules × 6.241509e+18
For a page dedicated to this direction, see Joule to Electronvolt.
Electronvolt vs. Joule
| Aspect | Electronvolt | Joule |
|---|---|---|
| Family | non-SI unit accepted for use with the SI, common in physics | SI derived unit |
| Typical use | Particle physics (particle accelerator energies are often quoted in GeV or TeV) | Physics and engineering energy calculations |
| Where it's used | Standard unit throughout particle physics, atomic physics, and chemistry worldwide | Standard scientific and engineering energy unit worldwide |
Understanding the Electronvolt
Electronvolt (eV) measures energy. The energy gained by a single electron accelerated through an electric potential difference of one volt — a very small amount of energy, exactly 1.602176634 × 10⁻¹⁹ joules. It is classified as a non-SI unit accepted for use with the SI, common in physics.
Where it's used: Standard unit throughout particle physics, atomic physics, and chemistry worldwide
Uses of the Electronvolt today
- Particle physics (particle accelerator energies are often quoted in GeV or TeV)
- Atomic and molecular energy levels
- Semiconductor band-gap energies
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.
Electronvolt — sources
- BIPM SI Brochure, 9th edition — Electronvolt listed as a non-SI unit accepted for use with the SI, with its exact value fixed via the elementary charge.
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 electronvolt?
1 electronvolt equals 1.602177e-19 joules, using the exact defined conversion factor rather than an estimate.
How do I convert electronvolt to joule?
Multiply the electronvolt value by 1.602177e-19. The converter above does this instantly to whatever precision you set.
How do I convert joule back to electronvolt?
Use the reverse factor: 1 joule equals 6.241509e+18 electronvolts. You can also use the swap control in the converter above to flip the direction instantly.
What is a electronvolt?
Electronvolt (eV) measures energy. The energy gained by a single electron accelerated through an electric potential difference of one volt — a very small amount of energy, exactly 1.602176634 × 10⁻¹⁹ joules. It is classified as a non-SI unit accepted for use with the SI, common in physics.
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 electronvolt to joule conversion exact?
Yes. The energy gained by a single electron accelerated through an electric potential difference of one volt — a very small amount of energy, exactly 1.602176634 × 10⁻¹⁹ joules. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the electronvolt still used today?
Standard unit throughout particle physics, atomic physics, and chemistry worldwide