Convert Watt-Hour to Electronvolt (Wh → eV)

Converting watt-hours 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 watt-hours

   Start with the number of watt-hours (Wh) you want to convert.
2. 2
   Multiply by 2.247 × 10^22

   The conversion factor from Wh to eV is 2.247 × 10^22. 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 watt-hours by 2.247 × 10^22. For the reverse direction, multiply by 4.45 × 10^-23.

• ✓1 Wh = 3600 J = 0.001 kWh.
• ✓Battery mAh × V = Wh. A 3000 mAh phone battery at 3.7 V = 11.1 Wh.
• ✓Airline limits lithium batteries to 100 Wh for carry-on.

• ✗Confusing mAh with Wh — need voltage to convert.
• ✗Using Wh when kWh is more appropriate for large batteries.
• ✗Forgetting the voltage in battery capacity calculations.

What is the Watt-Hour?

The watt-hour equals exactly 3,600 joules and is the standard unit for small-battery capacity, household electrical energy, and renewable-energy storage. A smartphone battery stores roughly 12–15 Wh, a laptop battery 50–100 Wh, and an electric car battery 60,000–100,000 Wh (60–100 kWh). The watt-hour represents the energy delivered by a 1-watt device running for 1 hour. It is the natural unit for connecting power (watts) to time, which is why electric utilities bill in kilowatt-hours. The watt-hour relates to the joule (3,600 J = 1 Wh), the kilowatt-hour (1,000 Wh = 1 kWh), and the BTU (1 Wh ≈ 3.412 BTU). Battery capacity, solar panel output (Wh per day), and energy storage system specifications all rely on the watt-hour as the base small-energy unit.

• Laptop and phone battery capacity
• Portable power banks and UPS
• Home solar panel daily output

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