Joule ↔ Electron-Volt Converter

For atomic and particle-physics scales: 1 eV = 1.602176634 × 10⁻¹⁹ J.

Inputs

Result

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General calculation reads

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How to use this calculator

  • Pick direction.
  • Enter value.
  • Read result, auto-scaled to keV/MeV/GeV.

About this calculator

The electron-volt is the natural energy unit in atomic and particle physics. 1 eV = the kinetic energy gained by one electron accelerating through 1 V. Common scales: chemical bonds ~1-5 eV, X-rays keV to MeV, particle physics MeV to GeV (LHC produces TeV-scale events).

Frequently asked

Why use eV?+
Atomic/molecular energies are tiny in joules (10⁻¹⁹). Using eV gives single-digit numbers that are easy to think about.
Common eV scales?+
Visible photon: 1.5-3 eV. Hydrogen ionization: 13.6 eV. X-ray: keV. Nuclear binding: MeV. LHC collisions: TeV.
eV vs joules in everyday life?+
You won't use eV outside science. A 100W bulb running for 1 second emits 100 J ≈ 6 × 10²⁰ eV — astronomically many photons.
Photon energy from wavelength?+
E (eV) ≈ 1240 / λ (nm). 500 nm visible photon ≈ 2.48 eV.
Where does the exact 1.602 e-19 come from?+
It's the elementary charge in coulombs. Exact since the 2019 SI redefinition.

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