Photon Energy Calculator

About this calculator

This calculator finds a photon's energy from its wavelength using E = hc/λ, where h is Planck's constant, c is the speed of light, and λ is the wavelength; it also reports the corresponding frequency (f = c/λ). Shorter wavelengths (like UV or X-rays) carry more energy per photon than longer ones (like infrared or radio), since energy is inversely proportional to wavelength.

Physics and chemistry students, and researchers in spectroscopy or photochemistry, use it to convert between a spectral line's wavelength and its energy in electronvolts (eV) or joules — useful for identifying whether a photon can ionize an atom, drive a photochemical reaction, or match an electronic transition. Enter a wavelength to get the energy and frequency.