What is the energy of a visible light photon?

Visible light spans about 1.65 eV (red, 750 nm) to 3.1 eV (violet, 400 nm).

How does photon energy relate to temperature?

The peak frequency of thermal radiation is proportional to temperature (Wien law). At room temperature, thermal photons are in the infrared.

Can a photon have any energy?

In principle yes, from radio waves (tiny energy) to gamma rays (MeV or more). The energy is quantised for a given frequency but the frequency itself is continuous.

Free Photon Energy-Frequency Calculator

Calculate the energy of a photon from its frequency using E = h * f, the Planck-Einstein relation.

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Frequency

Energy

0.0000000000000000003313000 J

Energy (eV)2.068040 eV

Wavelength0.000000599600 m

Energy vs Frequency

View formula & how it works →

Photon Energy from Frequency

A photon's energy is directly proportional to its frequency.

Formula

E = h f

*h* = 6.626 x 10^-34 J s (Planck constant)

*f* = frequency in Hz

The wavelength is lambda = c / f. Higher frequency (shorter wavelength) means higher energy.

Example Calculation

Green light at 500 THz (5e14 Hz).

01E = h f
02E = 6.626e-34 * 5e14
03E = 3.313e-19 J
04E = 3.313e-19 / 1.602e-19 = 2.069 eV
05lambda = 3e8 / 5e14 = 6e-7 m = 600 nm

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