Energy Converter: eV to kJ/mol, Joule, calorie, kWh and wavenumber
Scientific energy conversion tool with two modes. Energy mode converts between 15 units grouped by family: SI (J, kJ, MJ), practical (Wh, kWh, cal, kcal), atomic (eV, keV, MeV, Eₕ) and other (erg, L·atm, BTU, cal·IT). Molar energy mode bridges energy per mole and per particle —J/mol, kJ/mol, kcal/mol, eV per particle, wavenumber (cm⁻¹) and thermal RT— through the Avogadro and Planck constants.
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When to use this tool
Quick conversion across physics, chemistry, biology and geosciences: bond energies, band gaps and ionization energies in eV ↔ kJ/mol, Arrhenius activation energies (kJ/mol ↔ kcal/mol), pressure–volume work (L·atm ↔ J), statistical thermodynamics (comparing a barrier with RT at a given temperature), spectroscopy (transitions in cm⁻¹ ↔ kJ/mol), computational chemistry (Hartree, Eₕ) and metabolic or nutritional energy (kcal, kWh).
How it works
Pick the mode with the Energy / Molar energy selector. In Energy mode you type a value, choose source and target units, and the result and applied formula appear instantly; the 'Show all equivalents' panel lists the value across all 15 units at once. Molar energy mode is the differentiator: it converts per-particle energy into per-mole energy —for example, a 1 eV band gap equals 96.485 kJ/mol (the Faraday constant), and a 1000 cm⁻¹ infrared transition equals 11.963 kJ/mol— using Avogadro's number and the hc product. It includes the thermal energy RT, whose value depends on temperature: that is why molar mode shows a temperature field (default 298.15 K = 25 °C), handy for judging whether an energy barrier is large or small compared with thermal agitation. A precision detail: the thermochemical calorie (4.184 J) is treated as a distinct unit from the International Table calorie (4.1868 J), something most converters conflate. Because a molar energy and a total energy have different dimensions, switching modes does not carry the value across.