Convert Electronvolts to Calories
Convert Electronvolts (eV) to Calories (cal) instantly and accurately.
Conversion Formula
cal = eV × 3.829294058e-20
About Electronvolts
An electronvolt (eV) is the kinetic energy gained by one electron accelerated through 1 volt - exactly 1.602176634 × 10⁻¹⁹ J (fixed by the 2019 SI revision). It is the natural energy unit of atomic and particle physics: visible light photons carry 1.7-3.1 eV; hydrogen ionisation requires 13.6 eV; X-ray photons span 100 eV-100 keV; protons at the LHC reach 6.5 TeV. Rest masses use eV/c²: electron 0.511 MeV, proton 938.3 MeV, Higgs boson 125 GeV. Nuclear binding energy peaks at ~8 MeV/nucleon for iron-56. 1 eV = 1.602176634 × 10⁻¹⁹ J.
About Calories
A calorie (cal) - the thermochemical calorie - is exactly 4.184 J, defined as the heat to raise 1 g of water by 1°C. Standard since 1954. The calorie is the fundamental unit of heat measurement in thermochemistry: glucose combustion releases 669.9 kcal/mol; water vaporisation requires 539.7 cal/g. Bond dissociation energies in quantum chemistry are often quoted in kcal/mol. Note: the dietary Calorie (capital C) on food labels is 1 kcal = 4,184 J - a factor-of-1,000 difference that causes persistent confusion. 1 cal = 4.184 J = 1.163 × 10⁻³ Wh.
Quick Reference Table
| Electronvolts (eV) | Calories (cal) |
|---|---|
| 1 eV | 3.829 × 10-20 cal |
| 2 eV | 7.659 × 10-20 cal |
| 5 eV | 1.915 × 10-19 cal |
| 10 eV | 3.829 × 10-19 cal |
| 25 eV | 9.573 × 10-19 cal |
| 50 eV | 1.915 × 10-18 cal |
| 100 eV | 3.829 × 10-18 cal |