Electron Volt (eV) Converter
Convert between electron volts (eV), keV, MeV, GeV, TeV, joules, kcal, and temperature.
Includes wavelength and frequency equivalents for photons.
What Is an Electron Volt? An electron volt (eV) is the kinetic energy gained by one electron when accelerated through an electric potential difference of 1 volt. 1 eV = 1.602176634×10⁻¹⁹ joules (exact — fixed by 2019 SI redefinition). It is the natural energy unit for atomic, nuclear, and particle physics — where joules are far too large. One joule is approximately 6.242×10¹⁸ eV.
Energy Scale in Physics Chemical bond energy: 1–10 eV. X-ray photons: 100 eV – 100 keV. Nuclear binding energy per nucleon: ~8 MeV. Proton rest mass: 938 MeV. LHC collision energy: 13–14 TeV. Ultra-high-energy cosmic rays: up to 10²⁰ eV. Room temperature thermal energy (kT at 300 K): ~0.0259 eV ≈ 26 meV. Visible light photon: 1.8–3.1 eV (red → violet).
Photon Energy-Wavelength Relation E = hf = hc/λ Where h = 6.626×10⁻³⁴ J·s, c = speed of light, f = frequency, λ = wavelength. At 1 eV: λ = 1240 nm (near infrared). At 1 keV: λ = 1.24 nm (soft X-ray). Quick formula: E(eV) × λ(nm) = 1240 eV·nm.
Mass-Energy Equivalence From E = mc², mass can be expressed in eV/c²: Electron: 0.511 MeV/c². Proton: 938.3 MeV/c². Higgs boson: ~125.1 GeV/c². Top quark: ~173 GeV/c² — the heaviest known elementary particle.
Temperature Equivalence E = k_B × T → T = E/k_B 1 eV corresponds to T = 11,604 K (very hot plasma). Solar core temperature ~15 million K → kT ≈ 1.3 keV. This is why nuclear fusion requires such extreme temperatures.
Common eV Units meV (millielectron volt) = 10⁻³ eV — thermal energies, phonons, superconductor gaps. eV — atomic/molecular physics, chemistry. keV (kiloelectron volt) = 10³ eV — X-ray photons, inner-shell electrons. MeV (megaelectron volt) = 10⁶ eV — nuclear physics, gamma rays. GeV (gigaelectron volt) = 10⁹ eV — particle physics, W/Z bosons. TeV (teraelectron volt) = 10¹² eV — LHC collider energies.