Convert Electronvolts to Kilocalories
Convert Electronvolts (eV) to Kilocalories (kcal) instantly and accurately.
Conversion Formula
kcal = eV × 3.829294058e-23
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 Kilocalories
A kilocalorie (kcal) - the food Calorie (capital C) on US and Canadian nutrition labels - is exactly 4,184 J. WHO recommends ~2,000-2,500 kcal/day for adults. Energy density of nutrients: fat 9 kcal/g, carbohydrate 4 kcal/g, protein 4 kcal/g, ethanol 7 kcal/g. Running at 10 km/h burns ~600-800 kcal/h. Standard free energy of ATP hydrolysis is approximately −7.3 kcal/mol (−30.5 kJ/mol). Pre-SI thermodynamic tables in the US and Japan use kcal/mol for reaction enthalpies. 1 kcal = 4,184 J = 4.184 kJ = 3.968 BTU = 1.163 Wh.
Quick Reference Table
| Electronvolts (eV) | Kilocalories (kcal) |
|---|---|
| 1 eV | 3.829 × 10-23 kcal |
| 2 eV | 7.659 × 10-23 kcal |
| 5 eV | 1.915 × 10-22 kcal |
| 10 eV | 3.829 × 10-22 kcal |
| 25 eV | 9.573 × 10-22 kcal |
| 50 eV | 1.915 × 10-21 kcal |
| 100 eV | 3.829 × 10-21 kcal |