Volts to eV Calculator - Potential to Electron-Volt Energy

Agarapu Ramesh — Editor and content reviewer
Editorially reviewed Reviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026 | Standard electrical engineering formulas

A volt is energy per charge. An electron-volt is the energy gained by one electron moving through one volt. For one electron, volts and eV have the same numeric value, but the units are describing different things.

Formula at a glance

  • eV = volts x charge in elementary-charge units
  • for one electron: eV = V
  • J = eV x 1.602176634e-19

Field note: The number can match while the meaning changes. 5 V is a potential difference. 5 eV is an energy.

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Volts to eV Calculator

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About eV

1 eV = energy of 1 electron through 1V
Common in semiconductor physics

How to use the Volts to eV Calculator

Use this as a unit check for energy, power and time. Keep the time period honest, because a one-hour run and a one-month run can make the same load look completely different.

Worked example

Example: one electron through 5 V gains 5 eV. A particle with charge 2e through 5 V gains 10 eV.

Practical checks before you trust the number

  • Use this for microscopic charge and particle energy, not home electrical loads.
  • Check whether charge is given in coulombs or elementary charges.
  • The elementary charge conversion to joules is exact by SI definition.

Common mistake

The number can match while the meaning changes. 5 V is a potential difference. 5 eV is an energy.

Sources and references

Related calculators

Frequently Asked Questions

eV = V × n, where n is the number of electron charges. For 1 electron crossing 5 V, the energy gained is 5 eV. This is just the definition of the electron volt — energy per electron per volt — applied directly. Used constantly in physics and chemistry for energy levels and ionization.

E (eV) = V × n_e, where n_e is the number of electrons. For one electron, eV equals V numerically. So accelerating an electron through 25 V gives it 25 eV of kinetic energy. This works only for the elementary charge — for ions with multiple charges, scale by their charge state.

An electron crossing 5 V gains exactly 5 eV of kinetic energy. That's how the electron volt is defined: the energy of one electronic charge moved through one volt. Direct one-to-one numerical conversion for a single electron.

Because energy in joules equals charge times voltage (E = QV). The electron volt simplifies this for the electron's charge: 1 eV = 1 e × 1 V. For ions with multiple charges (like Cu²I), the energy gained per volt doubles, so charge state matters in the calculation.

The electron charge: e = 1.602 × 10I¹I C. This is the standard reference. For doubly-ionized particles like alpha (charge 2e), the energy per volt doubles. So always check the charge state when working with ions in mass spectrometry or accelerator beams.

Yes, exactly the use case. Electrons accelerated through V volts gain V eV of kinetic energy (in non-relativistic terms). At very high V (above 100 kV), relativistic corrections become important, and the kinetic energy formula deviates slightly from the simple V × n_e relation.

Yes. Physics problems in atomic spectra, photoelectric effect, and quantum mechanics all use eV. A calculator converts between volts (potential), eV (energy), and joules (SI energy) seamlessly. Useful for homework and for engineering work in vacuum tubes and electron-beam systems.