eV to Joules Converter

Precision physics converter for atomic, nuclear, and particle physics: eV, keV, MeV, GeV ⇄ J. Uses CODATA 2018 / 2019 SI exact value for the elementary charge.

1 eV = 1.602176634×10⁻¹⁹ J (exact)

Source: 2019 SI redefinition, e = 1.602176634×10⁻¹⁹ C, 1 eV = e × 1 V = e J.

Quick reference

Energy In Joules Notes
1 eV1.602176634×10⁻¹⁹ Jsingle electron accelerated by 1 V
1 keV1.602176634×10⁻¹⁶ JX-ray energies
1 MeV1.602176634×10⁻¹³ Jnuclear scale
1 GeV1.602176634×10⁻¹⁰ Jparticle physics

How the conversion works

Definition: 1 eV is the energy gained by an electron when it is accelerated through an electric potential difference of 1 volt.

Since the elementary charge is exactly e = 1.602176634×10⁻¹⁹ C, and 1 V × 1 C = 1 J, we get:

1 eV = 1.602176634×10⁻¹⁹ J (exact)

So, generally:

J = eV × 1.602176634×10⁻¹⁹

eV = J ÷ 1.602176634×10⁻¹⁹

Why use eV?

In atomic, nuclear, and high-energy physics, energies are tiny in SI, so eV, keV, MeV, GeV are more readable than writing 10⁻¹³ J everywhere.

FAQ

1. Is this value exact?

Yes. Since 2019 the elementary charge is an exact constant in SI, so 1 eV in joules is exact too.

2. What about kJ/mol conversions?

That’s a chemistry-style conversion using Avogadro’s number. This page focuses on the pure eV ⇄ J physics conversion, but you can derive it: 1 eV × Nₐ ≈ 96.485 kJ/mol.

3. Which one should I report in a lab report?

Use joules for SI purity, but it’s perfectly acceptable to give results in eV/keV/MeV and mention the exact factor used.