Photon Energy Calculator

Created by Miłosz Panfil, PhD
Reviewed by Bogna Szyk and Steven Wooding
Last updated: Sep 05, 2022

With this photon energy calculator, you can explore the relationship between the wavelength and frequency of the photon and its energy. Read the text below to find out how to calculate the energy of a photon and what is Planck's equation.

Planck's equation

The light seems to us to have a wavy character. It diffracts, interferes, and refracts. However, at a microscopic level, it is carried by a minuscule quantum of energy called the photon. The energy of a photon depends solely on its wavelength or frequency. Because light travels, well, at the speed of light, we can use either frequency or wavelength to describe it. You can check the wavelength calculator to explore the relationship between the wavelength and frequency.

Coming back to photons, what is their energy? The energy of a single photon is a tiny number given by Planck's equation. Planck's equation relates the frequency of a photon to its energy through a Planck constant hh equal to:

h=6.6261×1034 Js\small h = 6.6261 \times 10^{-34}\ \text{J}\cdot\text{s}

The Planck constant is in the units (energy)·(time), and you can think of it as a conversion factor from energies to frequencies.

How to calculate the energy of a photon

Planck's photo energy equation is:

E=hcλ=hf\small E = \frac{hc}{\lambda} = hf


  • EE – Energy of a photon;
  • hh – Planck constant;
  • cc – Speed of light;
  • λλ – Wavelength of a photon; and
  • ff – Frequency of a photon.

This equation gives us the energy of a single, indivisible quanta of light, and we can think of light as a collection of particles. The opposite is also true. We can think about ordinary particles, like electrons, as waves. Check De Broglie wavelength calculator to learn more about this concept.

Energy of a photon calculator

The energy of a single photon is a small number because the Planck constant is ridiculously tiny. The energy of a single photon of green light of a wavelength of 520 nm has an energy of 2.38 eV. You can use the photon energy calculator to explore further the relationship between the photon energy and its frequency or wavelength.

Miłosz Panfil, PhD
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