Electron Volt (eV) Converter
Convert energy between electron volts, meV, keV, MeV, GeV, TeV, joules and erg, with the matching photon wavelength, temperature and mass.
Type in any field and the others update instantly.
An electron volt (eV) is the amount of energy gained by a single electron when it accelerates through an electric potential difference of one volt.
Exact definition: 1 eV = 1.602176634 × 10⁻¹⁹ joules (exact, by definition since 2019)
This is an extremely tiny amount of energy in everyday terms, but it is perfectly suited to atomic and particle physics, where energies are naturally at this scale.
Unit hierarchy:
- 1 meV = 0.001 eV (millielectron volt, the scale of thermal and vibrational energy)
- 1 keV = 1,000 eV (kiloelectron volt)
- 1 MeV = 1,000,000 eV (megaelectron volt)
- 1 GeV = 1,000,000,000 eV = 10⁹ eV (gigaelectron volt)
- 1 TeV = 10¹² eV (teraelectron volt, the LHC scale)
Converting to joules and ergs:
- 1 eV = 1.602176634 × 10⁻¹⁹ J
- 1 J = 6.2415090745 × 10¹⁸ eV
- 1 erg = 10⁻⁷ J = 6.2415090745 × 10¹¹ eV
Energy scale reference:
| Phenomenon | Energy |
|---|---|
| Visible light photons | 1.8 – 3.1 eV |
| UV photons | 3.1 – 124 eV |
| X-ray photons | 100 eV – 100 keV |
| Gamma rays | > 100 keV |
| Chemical bonds | 1 – 10 eV |
| Nuclear reactions | 1 – 10 MeV |
| LHC proton collisions | ~13 TeV |
| Thermal energy at room temperature | ~0.025 eV |
Three things the eV doubles as
Because the electron volt is an energy, three other quantities fall straight out of it, and the panel above prints all three:
- Photon wavelength. E = hc/λ gives the tidy constant λ(nm) = 1,239.84 / E(eV). A 2 eV photon is 620 nm, which is orange. This is why the table above can list light by energy at all.
- Temperature. E = kT, and Boltzmann’s constant is 8.617 × 10⁻⁵ eV per kelvin, so 1 eV corresponds to about 11,600 K. Room temperature, 300 K, is 25.9 meV, which is where that 0.025 eV row comes from.
- Mass. E = mc² lets particle masses be quoted as energies. The electron is 0.511 MeV, the proton 938.3 MeV. Physicists write “MeV” and mean “MeV/c²”, and everyone in the room knows.
Applications: The electron volt is used throughout particle physics, atomic physics, nuclear physics, and photonics. When an accelerator is described as running at 13 TeV, that is the combined collision energy of two beams, so each proton carries 6.5 TeV. A single 7 TeV proton carries roughly the kinetic energy of a flying mosquito, which sounds absurd until you remember the mosquito outweighs the proton by about twenty-one orders of magnitude.
How we build and check this converter
This converter runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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