The electronvolt is the energy an electron gains crossing one volt – a convenient unit for atoms and particles. An ion with charge 2e accelerated through 1 kV gains 2 keV.
How to use the Volts to Electron-Volts Calculator
- Voltage V
- Charge (in units of e)
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the voltage and the particle’s charge in units of the elementary charge.
Inputs explained
| Field | What to enter |
|---|---|
| Voltage V | Units: V, kV, mV |
| Charge (in units of e) | A number |
What each result means
- Energy = [Voltage V]×abs([Charge (in units of e)])
- Energy in keV = [Voltage V]×abs([Charge (in units of e)])÷1000
- Energy in joules = [Voltage V]×abs([Charge (in units of e)])×1.602176634e-19
Example values
How the main result changes when Voltage V changes and everything else stays at the example values above:
| Voltage V (V) | Energy (eV) |
|---|---|
| 500 | 500 |
| 750 | 750 |
| 1,000 | 1,000 |
| 1,250 | 1,250 |
| 1,500 | 1,500 |
| 2,000 | 2,000 |
Formula
E (eV) = V × q/e, E (J) = q·V
Worked example
Inputs — Voltage V: 1,000 V; Charge (in units of e): 1.
Results — Energy = 1,000 eV; Energy in keV = 1 keV; Energy in joules = 1.6022e-16 J.
Key terms
- Electronvolt
- Energy gained by charge e across 1 V.
Frequently asked questions
Is an electronvolt a unit of voltage?
No – it is a unit of energy.
How many joules is 1 eV?
1.602176634 × 10⁻¹⁹ J.
What energy does a doubly charged ion gain?
Twice the voltage in eV.
Where are eV used?
Atomic, nuclear and particle physics, and semiconductors.