Volts to Electron Volts Calculator

Understanding Volts and Electron Volts

A volt (V) is the SI unit of electric potential, defined as one joule of energy per coulomb of charge. It describes the pressure pushing electrons through a conductor or the potential difference across a component.

An electron volt (eV) is a non-SI unit of energy commonly used in physics and chemistry. It represents the kinetic energy acquired by a single electron when accelerated from rest through a potential difference of exactly one volt. The relationship is precise: 1 eV = 1.602176634 × 10⁻¹⁹ joules.

The elementary charge (e) is the magnitude of electric charge carried by one electron, approximately 1.602 × 10⁻¹⁹ coulombs. This fundamental constant appears in both atomic physics and this conversion.

Electron volts dominate discussions of:

• Ionisation energies in atoms
• Band gaps in semiconductors
• Radiation energy in medical imaging
• Particle accelerator experiments
• Photoelectric effect thresholds

Conversion Formula: Volts to Electron Volts

To find energy in electron volts, multiply the applied voltage by the electric charge passing through. The formula uses the relationship between potential difference and work done on a charge carrier.

• eV — Energy in electron volts
• V — Voltage applied, measured in volts
• Q — Electric charge in coulombs
• n — Number of elementary charges
• e — Elementary charge (1.602 × 10⁻¹⁹ C)

Joule Conversion and Energy Scales

Although electron volts are convenient for atomic-scale calculations, the joule is the SI unit of energy and appears in most macroscopic physics problems. The conversion factor between them is fixed:

1 eV = 1.602176634 × 10⁻¹⁹ joules

Inversely, 1 joule ≈ 6.242 × 10¹⁸ electron volts.

This enormous ratio explains why electron volts exist: stating an atomic ionisation energy as 13.6 eV is far clearer than writing 2.18 × 10⁻¹⁸ J. Similarly, thermal energy at room temperature (about 0.026 eV) shows why room-temperature thermal fluctuations cannot ionise most atoms.

To convert your calculated electron volts to joules, multiply by 1.602 × 10⁻¹⁹.

Practical Considerations When Converting Voltage to Energy

Common pitfalls and real-world context when working with volts and electron volts.

1. Charge quantity must be explicit — The energy result depends entirely on how much charge flows. A 100 V potential alone tells you nothing—you need the charge in coulombs or the number of electrons involved. One electron at 100 V gives 100 eV; one million electrons gives 100 meV total.
2. Sign of charge matters in calculations — Work and energy transfer depend on the direction of charge flow and the sign of the potential difference. In a battery, electrons move from negative to positive terminal; the potential difference reverses if you flip the measurement direction, flipping the energy sign.
3. Elementary charge ≠ coulomb confusion — Using 1.602 × 10⁻¹⁹ coulombs per electron is essential. If you accidentally use coulombs directly without this factor, your answer will be off by many orders of magnitude. Always check your units.
4. eV applies to single particles, not bulk current — Electron volts describe energy per charge carrier. A 10 A current at 5 V does not yield 50 eV; instead, each electron carries 5 eV, and the total power is 50 watts distributed across many charge carriers passing per second.

Real-World Applications

Electron volts appear constantly in modern physics and engineering:

• Semiconductor design: Silicon band gap ≈ 1.1 eV; germanium ≈ 0.66 eV. These values determine which photons can generate electrical current in solar cells.
• X-ray tubes: Electrons accelerated through 50,000 volts produce 50 keV X-rays, energetic enough to penetrate tissue.
• Particle physics: The Large Hadron Collider accelerates protons to TeV (10¹² eV) energies, far beyond chemical bonding energies.
• Thermal physics: Room temperature is roughly 0.025 eV. This predicts which energy levels are populated at ambient conditions.
• Photoelectric effect: A metal with 4 eV work function requires ultraviolet light (photons > 4 eV) to emit electrons.