Joules to eV Converter

How to convert joules to electronvolts

1 joule = 6.241509074e+18 electronvolts. To convert joules to electronvolts, multiply by 6.241509074e+18. The joule is the SI unit of energy, one newton-meter. An electronvolt is the energy one electron gains across 1 volt, exactly 1.602176634 × 10⁻¹⁹ J.

Worked examples

• 1e-19 joules = 0.624151 eV (1e-19 × 6.2415091e+18)
• 3.2e-19 joules = 1.99728 eV (3.2e-19 × 6.2415091e+18)
• 1 joule = 6.24151e+18 eV (1 × 6.2415091e+18)

Where this conversion comes up

Joules are used for physics and electrical energy; electronvolts for atomic, particle and semiconductor physics, photon energies and band gaps. Used after calculating a photon's energy with E = hf or E = hc/λ in joules, when the answer is expected in electronvolts. Divide by 1.602176634 × 10⁻¹⁹: a 3.2 × 10⁻¹⁹ J photon (about 620 nm, orange light) is 2 eV. One joule is a huge amount at this scale, 6.24 × 10¹⁸ eV.

Quick estimate

Multiply by 6.24 × 10¹⁸, or divide by 1.6 × 10⁻¹⁹.

Common mistakes

• Dividing instead of multiplying. A electronvolt is smaller than a joule, so the number of electronvolts must come out larger: 1e-19 joules = 0.624151 eV.
• Rounding too early. Keep the full factor until the last step; rounding 6.24e+18 to 6.2e+18 first puts large values noticeably off.

Going the other way? Use the ev to joules converter. Related energy converters: kj to calories, kcal to kj, kj to kcal, kwh to mwh, kj to j, j to kj.