Electronvolts to Kilojoules Converter

Common Conversions

eV	kJ
1	1.602e-22
10	1.602e-21
100	1.602e-20
1000	1.602e-19
10000	1.602e-18
100000	1.602e-17
1000000	1.602e-16
1000000000	1.602e-13
1000000000000	1.602e-10
1000000000000000	1.602e-7
1000000000000000000	0.0001602
1e+21	0.1602

Why this conversion matters in chemistry

An electronvolt is one electron's worth of charge moved through one volt — a tiny energy at the macroscopic scale (1 eV is 1.602 × 10⁻²² kJ) but the natural unit for individual photons, electrons, and molecular orbitals. The mole-scale conversion is much more useful: 1 eV per particle equals 96.485 kJ/mol, which is just Avogadro's number times the elementary charge expressed as kJ. The conversion is the bridge between a UV-visible band gap, a DFT energy, or an X-ray transition reported in eV and a thermochemistry table written in kJ/mol. Hematite's 2.1 eV band gap, for instance, sits comfortably above the 1.23 eV thermodynamic minimum per electron for water splitting — but real overpotentials and recombination losses are why hematite still needs an external bias to drive the reaction.

Formula

kJ = eV × 1.60218 × 10⁻²²

Worked Examples

1 eV = 1.602×10⁻²² kJ

One electronvolt for a single particle — vanishingly small at the macroscopic scale, which is why mol-based conversion is the practical move.

6.242×10²¹ eV = 1 kJ

The number of electronvolts that add up to one kilojoule — equivalently, 0.01 mol of single-eV events.

13.6 eV = 2.179×10⁻²¹ kJ

The ionization energy of a single hydrogen atom — the Rydberg energy, the foundational atomic-physics number.

1000 eV = 1.602×10⁻¹⁹ kJ

One keV — the photon energy range where soft X-ray and core-level photoemission spectroscopy operate.

Frequently Asked Questions

How do I convert eV to kJ?

For a single-particle value, multiply by 1.602 × 10⁻²². For a per-mole comparison — which is usually what chemistry actually wants — use 1 eV/particle = 96.485 kJ/mol. That factor comes from multiplying the elementary charge expressed as an energy (1.602 × 10⁻¹⁹ J/eV) by Avogadro's number, then converting J to kJ.

Why is the per-particle number so small?

An electronvolt is one electron's worth of charge moved through one volt. That's a vanishingly small amount of energy at the macroscopic scale. Multiplying by Avogadro's number scales it up to a per-mole value where the chemistry becomes recognizable: 1 eV × 6.022 × 10²³ ≈ 96,485 J/mol = 96.485 kJ/mol.

When does this conversion come up?

Computational chemistry — DFT outputs are often in eV per atom or per molecule, and need converting to kJ/mol for comparison with experimental thermodynamics. UV-visible spectroscopy bandgaps in eV translate to per-mole electronic energies the same way. Photoelectron spectroscopy and X-ray transitions also live in eV by tradition.