Convert Electronvolt to Megajoule (eV → MJ)

Converting electronvolts to megajoules 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^-25

   The conversion factor from eV to MJ is 1.602 × 10^-25. Multiply your value by this number.
3. 3
   Read the result in megajoules

   The result is your value in megajoules (MJ).

Multiply the value in electronvolts by 1.602 × 10^-25. For the reverse direction, multiply by 6.242 × 10^24.

• ✓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 Megajoule?

The megajoule equals 1,000,000 joules (or 1,000 kilojoules) and is used for measuring fuel energy content, large-scale electrical work, and industrial heat applications. The energy content of food and fuel is often quoted in MJ: a kilogram of gasoline contains about 46 MJ, natural gas has 38 MJ per cubic meter, and a kilogram of coal yields 24 MJ. Vehicle fuel-economy and energy-efficiency calculations use MJ to compare disparate energy sources. Industrial process heating, boiler outputs, and large machinery energy ratings are commonly given in MJ per cycle or MJ per hour. The megajoule relates to the joule (10⁶ J = 1 MJ), the kilojoule (1,000 kJ = 1 MJ), the kilowatt-hour (1 kWh = 3.6 MJ), and the BTU (1 MJ ≈ 948 BTU). For electricity-grid energy accounting, the equivalent kilowatt-hour or megawatt-hour is more common than MJ.

• Fuel energy content reporting
• Natural gas billing in some countries
• Industrial energy consumption