Electronvolt to Joules Converter

Multiply the energy in electronvolts by 1.602176634e-19, the exact number of joules in one electronvolt. For example, 5 eV equals 5 times 1.602176634e-19, which is about 8.01e-19 J. For keV, MeV, GeV, or TeV, first scale to electronvolts by the matching power of ten (1 keV is 1,000 eV and 1 MeV is 1,000,000 eV), then multiply.

Since the 2019 redefinition of SI units, the elementary charge is fixed at exactly 1.602176634e-19 coulombs. One electronvolt is the energy a single elementary charge gains moving through a potential difference of one volt, so 1 eV equals that charge times one volt, giving 1.602176634e-19 J. Because the value is now a definition rather than a measurement, it carries no uncertainty.

They are electronvolts scaled by SI prefixes: 1 keV is a thousand eV, 1 MeV is a million eV, 1 GeV is a billion eV, and 1 TeV is a trillion eV. Physicists pick them by energy range, using keV for X-rays, MeV for nuclear and gamma energies, and GeV to TeV for particle accelerators. This converter accepts any of these units and reports the joule value plus the full ladder.

Yes. Binding and potential energies are often quoted as negative electronvolts, such as -13.6 eV for the hydrogen ground state. The conversion is a straight linear scaling, so a negative input simply returns a negative joule value, here about -2.18e-18 J.

An attojoule (aJ) is 1e-18 joule, which puts single-particle energies on a readable scale, since 1 eV is about 0.16 aJ. An erg is the CGS unit of energy, equal to 1e-7 joule, so 1 eV is about 1.60e-12 erg. This tool shows both next to the joule value so you can match whichever unit your source uses.

The conversion factor is exact, so the only limit is 64-bit floating point arithmetic, which keeps about 15 to 16 significant figures. That is far finer than any measured energy. Very small and very large results are shown in scientific notation so no digits are lost to rounding.