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Calculator for Mass, Energy and Momentum of Photons

Calculates the mass, energy and momentum of a single photon or a number of photons from the wavelength.

The rest mass of a photon is 0. But photons travel at the speed of light. The mass of a photon is calculated with the formula m=ℎ/(c*λ) with Planck's constant ℎ, the speed of light c in meters per second and the wavelength λ in meters. Einstein's equation E=mc² applies to energy. Finally, the momentum is the mass times the speed of light, p=mc.
Please enter the wavelength and the number of photons. The default for number of photons is 1*10⁰, i.e. 1.

Wavelength:	* 10^-12-9-6-30369 m
Number of photons:	* 10^036912151821242730
Mass:	* 10^-51-48-45-42-39-36-33-30-27-24-21-18-15-12-9-6-30 kg
Energy:	* 10^-42-39-36-33-30-27-24-21-18-15-12-9-6-30 J
Impulse:	* 10^-42-39-36-33-30-27-24-21-18-15-12-9-6-30 kg * m / s

Example: a photon in green light has a wavelength of 530*10^-9 meters. This means it has a mass of around 4.17*10^-36 kilograms.

For wavelengths see the spectrum calculator.

Although photons have no rest mass, they still carry energy and momentum. This is a consequence of their motion at the speed of light. This energy is greater the shorter the photon's wavelength. An X-ray photon with an extremely short wavelength therefore has far more energy than a photon of visible light or a radio wave photon. Photons are a central element in quantum physics and many modern technologies, such as photovoltaics, laser technology, and quantum communication. Here, wave-particle duality becomes apparent: depending on the experiment, photons sometimes behave like particles (as in the photoelectric effect) and sometimes like waves (as in interference phenomena). This duality was one of the most revolutionary discoveries of early quantum physics and led to the development of quantum mechanics. Photons are also the mediators of the electromagnetic force. They carry information between charged particles, for example, when electrons in an atom change their energy states. Without photons, there would be no light, no heat radiation, and no electromagnetic communication.

Last updated on 01/09/2026. Author: Jürgen Kummer

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