Electron-Volts to Volts Calculator
Convert energy in electron-volts (eV) to electrical potential in volts (V). Enter the energy and the charge — either in elementary-charge units (e) or in coulombs (C) — and press Calculate. The voltage is V = E / Q for elementary charge, or V = 1.602176565×10⁻¹⁹ × E / Q for coulombs. Everything runs locally in your browser.
Enter the energy in electron-volts
Type the energy E in electron-volts (eV). Plain numbers and exponent notation both work — e.g. 13.6 for a hydrogen ionization energy, or 1e6 for 1 MeV.
Pick the charge unit and enter the charge
Choose "Elementary charge unit" and enter the charge as a multiple of the proton/electron charge (e.g. 1 for a single electron or proton), or choose "Coulomb unit" and enter the charge in coulombs (e.g. 1.602176565e-19 C for one elementary charge). The charge cannot be zero.
Press Calculate, read volts
The voltage V in volts appears instantly, with the exact formula and your inputs shown underneath. Copy the result to your clipboard, or press Reset to clear everything and start over.
eV to volts formulas
- eV to volts calculation with elementary charge
- The voltage V in volts (V) is equal to the energy E in electron-volts (eV), divided by the electric charge Q in elementary charges (e): V(V) = E(eV) / Q(e). For example, 13.6 eV across a single elementary charge gives 13.6 / 1 = 13.6 V, and 1000 eV across 5 elementary charges gives 1000 / 5 = 200 V.
- eV to volts calculation with coulombs
- The voltage V in volts (V) is equal to 1.602176565×10⁻¹⁹ times the energy E in electron-volts (eV), divided by the electric charge Q in coulombs (C): V(V) = 1.602176565×10⁻¹⁹ × E(eV) / Q(C). For example, 500 eV across 3.20435313×10⁻¹⁹ C (two elementary charges) gives 250 V.
- Why is 1 eV across 1 elementary charge exactly 1 volt?
- An electron-volt is defined as the energy gained by a particle carrying one elementary charge e when it moves through a potential difference of one volt. Since e = 1.602176565×10⁻¹⁹ C, dividing 1 eV of energy by a charge of 1 e cancels the constant: V = E / Q = 1 eV / 1 e = 1 V. That is why the elementary-charge mode is a plain division.
- Which charge unit should I use?
- Use elementary charge units when counting particle charges — atomic and particle-physics problems quote ions and particles as multiples of e (H⁺ = 1 e, an alpha particle ≈ 2 e, Ca²⁺ = 2 e). Use coulombs when your charge is already a macroscopic SI quantity; remember one coulomb is about 6.24×10¹⁸ elementary charges, so eV-scale energies across coulomb-scale charges give tiny voltages (1 eV / 1 C = 1.602176565×10⁻¹⁹ V).
- Why does the calculator reject a charge of zero?
- Voltage is energy divided by charge, so Q = 0 would mean dividing by zero — no potential difference is defined for a particle with no charge. Enter any non-zero charge; the charge is a divisor here, not an offset.
- Where does the constant 1.602176565×10⁻¹⁹ come from?
- It is the elementary charge e expressed in coulombs — the magnitude of the charge of a single proton (and the negative of the electron's). This calculator uses the CODATA 2011 value 1.602176565×10⁻¹⁹ C for consistency with the reference definition; the 2019 SI redefinition fixed e at 1.602176634×10⁻¹⁹ C, a relative difference of about 4×10⁻⁸ which is far below any real measurement uncertainty.
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Copy result uses your clipboard only. Results assume ideal electrostatics; the constant used is CODATA 2011 (1.602176565×10⁻¹⁹ C).