Photon energy

Light carries energy in packets called photons. The energy of a single photon depends on its frequency (or wavelength):

$E=h\,f=\frac{h\,c}{\lambda}$

where $h=6.626\cdot10^{-34}\ \text{J·s}$ (Planck's constant) and $c=3\cdot10^8\ \tfrac{\text{m}}{\text{s}}$. The shorter the wavelength (toward violet and beyond — UV, X-rays), the greater the energy of the photon.

Enter the wavelength (in nm), the frequency, or the energy (in eV) — the calculator converts the remaining quantities, including the energy in joules and electronvolts ($1\ \text{eV}=1.602\cdot10^{-19}\ \text{J}$). The presets correspond to the colours of visible light.