Volts to Electron-Volts Calculator
Convert electrical potential in volts (V) to energy in electron-volts (eV). Enter the voltage and the charge — either in elementary-charge units (e) or in coulombs (C) — and press Calculate. The energy is E = V × Q for elementary charge, or E = V × Q / 1.602176565×10⁻¹⁹ for coulombs. Everything runs locally in your browser.
Enter the voltage in volts
Type the electrical voltage V in volts. Plain numbers and exponent notation both work — e.g. 12 for a car battery, 5 for a USB rail, or 1e6 for a megavolt accelerator stage.
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). A charge of zero is allowed and gives 0 eV.
Press Calculate, read electron-volts
The energy E in electron-volts appears, with the exact formula and your inputs shown underneath. Copy the result to your clipboard, or press Reset to clear everything and start over.
Volts to eV formulas
- Volts to eV calculation with elementary charge
- The energy E in electron-volts (eV) equals the voltage V in volts (V) times the charge Q in elementary charges (e): E(eV) = V(V) × Q(e). The elementary charge is the charge of a single electron, symbol e. For example, an electron accelerated through 12 V gains 12 V × 1 e = 12 eV, and a charge of 2.5 elementary charges moved through 3.7 V gains 3.7 × 2.5 = 9.25 eV.
- Volts to eV calculation with coulombs
- The energy E in electron-volts (eV) equals the voltage V in volts (V) times the charge Q in coulombs (C), divided by 1.602176565×10⁻¹⁹: E(eV) = V(V) × Q(C) / 1.602176565×10⁻¹⁹. For example, 100 V across 1×10⁻¹⁸ C gives about 624.15 eV, and 1 V across exactly 1.602176565×10⁻¹⁹ C — one elementary charge — gives exactly 1 eV.
- Why is 1 volt across 1 elementary charge exactly 1 electron-volt?
- An electron-volt is defined as the energy a particle carrying one elementary charge e gains when it moves through a potential difference of one volt. So E = V × Q = 1 V × 1 e = 1 eV by definition — the elementary-charge mode is a plain multiplication with no constant in sight.
- Which charge unit should I use?
- Use elementary charge units for particle and atomic problems — ions and particles are quoted as multiples of e (an electron = 1 e, an alpha particle ≈ 2 e, a Ca²⁺ ion = 2 e). Use coulombs when the charge is a macroscopic SI quantity; one coulomb is about 6.24×10¹⁸ elementary charges, so volt-scale potentials across coulomb-scale charges give astronomically large eV numbers (1 V × 1 C ≈ 6.24×10¹⁸ eV).
- Can the charge be zero or negative?
- Yes to both. Unlike the reverse conversion (eV to volts, where charge divides), here the charge multiplies, so Q = 0 is legal and simply gives 0 eV — no energy is transferred to a charge that isn't there. Negative charges give signed results (−5 V × 2 e = −10 eV), matching the sign convention of work done on the carrier.
- 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.
Going the other way? Use the electron-volts to volts calculator.
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).