Joules to Electronvolts Calculator
Convert energy in joules to electronvolts, kiloelectronvolts, and megaelectronvolts.
How Joules to eV works
The electronvolt is the energy gained by a single electron moving through a potential difference of one volt. It is a tiny amount of energy — exactly 1.602176634×10⁻¹⁹ joules — making it the natural unit for atomic and particle physics.
To convert joules to electronvolts, divide by 1.602176634×10⁻¹⁹. Because eV values are large when starting from everyday joule quantities, results are often expressed in keV (thousands) or MeV (millions) of electronvolts.
eV = J ÷ 1.602176634×10⁻¹⁹1 eV = 1.602176634×10⁻¹⁹ J (exact since the 2019 SI redefinition).
Joules to eV conversion table
| Joules↕ | Electronvolts↕ | MeV↕ |
|---|---|---|
| 1.6×10⁻¹⁹ J | ≈1 eV | 1×10⁻⁶ MeV |
| 1×10⁻¹⁵ J | 6,242 eV | 0.00624 MeV |
| 1×10⁻¹² J | 6.242×10⁶ eV | 6.242 MeV |
| 1×10⁻⁹ J | 6.242×10⁹ eV | 6,242 MeV |
| 1 J | 6.242×10¹⁸ eV | 6.242×10¹² MeV |
FAQ: Joules to eV
How many joules are in an electronvolt?
One electronvolt equals exactly 1.602176634×10⁻¹⁹ joules. This value is fixed by the 2019 SI redefinition of the elementary charge.
How do you convert joules to eV?
Divide the energy in joules by 1.602176634×10⁻¹⁹. For example, 1×10⁻¹⁵ J ÷ 1.602×10⁻¹⁹ ≈ 6,242 eV.
When is the electronvolt used?
Electronvolts are used in atomic, nuclear, and particle physics — for photon energies, binding energies, and particle accelerator ratings, where joules would be inconveniently small.