Convert Electronvolt to Joule (eV → J)

Converting electronvolts to joules is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in electronvolts

   Start with the number of electronvolts (eV) you want to convert.
2. 2
   Multiply by 1.602 × 10^-19

   The conversion factor from eV to J is 1.602 × 10^-19. Multiply your value by this number.
3. 3
   Read the result in joules

   The result is your value in joules (J).

Multiply the value in electronvolts by 1.602 × 10^-19. For the reverse direction, multiply by 6,241,509,074,460,763,000.

• ✓1 eV ≈ 1.602 × 10⁻¹⁹ J.
• ✓Particle physics scales: eV → keV → MeV → GeV → TeV (1000× each).
• ✓Photon energy (eV) × wavelength (nm) ≈ 1240.

• ✗Confusing eV with V (volt) — eV is energy, V is electric potential.
• ✗Mixing scales: treating MeV as twice eV — it's a million times larger.
• ✗Using eV for macroscopic energy — unwieldy numbers.

What is the Electronvolt?

The electronvolt equals approximately 1.602176634 × 10⁻¹⁹ joules (a tiny amount of energy) and is the standard unit in atomic physics, particle physics, and semiconductor electronics. Defined as the energy gained by an electron accelerated through a potential difference of 1 volt, the eV is the natural scale for atomic and molecular energies. The energy required to ionize a hydrogen atom is 13.6 eV, the band gap of silicon (relevant for transistors and solar cells) is 1.12 eV, and visible light photons carry 1.6–3.3 eV per photon. Particle physicists routinely use MeV (million eV), GeV (billion eV), and TeV (trillion eV): the Large Hadron Collider accelerates protons to 6.5 TeV. The eV relates to the joule (1 eV ≈ 1.602 × 10⁻¹⁹ J), the kilojoule per mole (96.485 kJ/mol per eV), and atomic mass units via E = mc². It is the universal energy unit in physics literature.

• Particle physics (TeV, GeV, MeV)
• Atomic and molecular physics
• Semiconductor band gaps

What is the Joule?

The joule is the SI unit of energy, work, and heat, named after English physicist James Prescott Joule (1818–1889). Defined as the energy transferred when a force of one newton acts over a distance of one meter (1 J = 1 N·m), the joule unifies mechanical work, electrical energy (1 J = 1 watt-second = 1 V·C), and thermal energy. A typical apple has about 250,000 joules of chemical energy when metabolized, lifting an apple 1 meter requires roughly 1 joule of mechanical work, and a single joule could light a 1-watt LED for one second. The joule is fundamental in physics, mechanical engineering, electrical engineering, and nutrition (European food labels show kilojoules). It relates to the kilojoule (1 kJ = 1,000 J), the calorie (1 cal = 4.184 J), the watt-hour (1 Wh = 3,600 J), and the BTU (1 BTU ≈ 1,055 J). Modern definitions of the kilogram and the Kelvin both reference the joule.

• Physics and engineering calculations
• Scientific nutrition measurement (European labels)
• Impact energy in engineering (Charpy test)