The joule is the SI derived unit of energy.
Joules to Electronvolts Converter — J to eV
Convert Joule (J) to Electronvolt (eV) using the exact conversion factor (1 joule = 6.241509e+18 electronvolt). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Joules to Electronvolts converter
Converter
Scientific Units Converter
Convert SI derived units, scientific notation-friendly units, atomic units, and lab measurements.
Context values
Some unit families need one extra value for a physically accurate result.
An electronvolt is the energy gained by an electron across one volt.
Result = input x 1 / 1.60217663e-19.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Joules to Electronvolts
Joule and Electronvolt are both scientific-measurement units, spanning everything from atomic and laboratory scales to astronomical distances — the kind of conversion that comes up constantly in physics, chemistry, and astronomy when a result needs to move between conventions used in different subfields. Joule is typically associated with standard scientific and engineering energy unit worldwide, while Electronvolt is typically associated with standard unit throughout particle physics, atomic physics, and chemistry worldwide.
Formula
electronvolts = joules × 6.241509e+18
This factor comes from each unit's defined relationship to the category's base unit: 1 joule equals 1 base unit, and 1 electronvolt equals 1.602177e-19 base units, so dividing one by the other gives the direct joule-to-electronvolt factor of 6.241509e+18.
Simple example
1 J × 6.241509e+18 = 6.241509e+18 eV
1 joule = 6.241509e+18 electronvolts.
Real-world example
10 J × 6.241509e+18 = 6.241509e+19 eV
10 joules = 6.241509e+19 electronvolts.
Conversion table
| Joule (J) | Electronvolt (eV) |
|---|---|
| 0.001 J | 6.241509e+15 eV |
| 0.01 J | 6.241509e+16 eV |
| 1 J | 6.241509e+18 eV |
| 10 J | 6.241509e+19 eV |
| 100 J | 6.241509e+20 eV |
| 1,000 J | 6.241509e+21 eV |
Reverse conversion: Electronvolt to Joule
6.241509e+18 eV × 1.602177e-19 = 0.9999999881 J
6.241509e+18 electronvolts = 0.9999999881 joules.
joules = electronvolts × 1.602177e-19
For a page dedicated to this direction, see Electronvolt to Joule.
Joule vs. Electronvolt
| Aspect | Joule | Electronvolt |
|---|---|---|
| Family | SI derived unit | non-SI unit accepted for use with the SI, common in physics |
| Typical use | Physics and engineering energy calculations | Particle physics (particle accelerator energies are often quoted in GeV or TeV) |
| Where it's used | Standard scientific and engineering energy unit worldwide | Standard unit throughout particle physics, atomic physics, and chemistry worldwide |
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.
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
Joule — sources
- BIPM SI Brochure — Coherent derived units — Defines the joule as the SI unit of energy.
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.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many electronvolts are in 1 joule?
1 joule equals 6.241509e+18 electronvolts, using the exact defined conversion factor rather than an estimate.
How do I convert joule to electronvolt?
Multiply the joule value by 6.241509e+18. The converter above does this instantly to whatever precision you set.
How do I convert electronvolt back to joule?
Use the reverse factor: 1 electronvolt equals 1.602177e-19 joules. You can also use the swap control in the converter above to flip the direction instantly.
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.
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.
Is the joule to electronvolt 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 joule still used today?
Standard scientific and engineering energy unit worldwide
Why does this category span everything from atomic to astronomical scales?
Scientific work spans an enormous range of physical scales, from atomic distances (measured in angstroms or atomic mass units) to interstellar distances (measured in astronomical units or parsecs), so this category groups SI-derived and scale-specific units that researchers commonly need to convert between within their field.