Convert Joule to Electronvolt (J → eV)

Converting joules to electronvolts 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 joules

   Start with the number of joules (J) you want to convert.
2. 2
   Multiply by 6,241,509,074,460,763,000

   The conversion factor from J to eV is 6,241,509,074,460,763,000. Multiply your value by this number.
3. 3
   Read the result in electronvolts

   The result is your value in electronvolts (eV).

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

• ✓1 J = 1 N·m = 1 W·s.
• ✓1 kWh = 3,600,000 J (3.6 MJ).
• ✓For nutrition 1 kcal = 4.184 kJ.

• ✗Confusing joule (energy) with newton (force).
• ✗Mixing joule with watt — watt is joule per second.
• ✗Using kJ when labels call for kcal on US nutrition.

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)

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