Electronvolts to Joules Converter

The Electronvolts to Joules Converter converts energy from electronvolts (eV) to joules (J) and attojoules (aJ) using the exact conversion factor 1 eV = 1.602176634 × 10⁻¹⁹ J. This factor was fixed as an exact value in the 2019 SI redefinition when the elementary charge was defined as exactly 1.602176634 × 10⁻¹⁹ coulombs.

The electronvolt is the standard energy unit in atomic, nuclear, and particle physics. It represents the kinetic energy gained by a single electron when accelerated through a potential difference of one volt. While incredibly small by everyday standards (about 10⁻¹⁹ J), the electronvolt is the natural scale for atomic and subatomic processes.

In practice, physicists use multiples of the electronvolt: keV (10³ eV) for X-ray energies, MeV (10⁶ eV) for nuclear reactions, GeV (10⁹ eV) for particle masses, and TeV (10¹² eV) for high-energy collider physics. The mass of a proton is about 938.3 MeV/c², and the Higgs boson has a mass of about 125.1 GeV/c².

Converting electronvolts to joules is necessary when connecting quantum-scale physics to macroscopic thermodynamics. For example, the thermal energy kT at room temperature (300 K) is about 0.0259 eV = 4.14 × 10⁻²¹ J. Chemical bond energies range from 1–10 eV per bond. Ionization energies and band gaps in semiconductors are routinely expressed in eV.

Our converter also provides results in attojoules (10⁻¹⁸ J), which provide a more readable scale for single-particle energies. One electronvolt equals approximately 0.1602 attojoules.