Calculators
Photon Energy Calculator
Calculate energy per photon in joules and electronvolts, plus frequency, from vacuum wavelength in nanometers. Runs privately in your browser.
Convert vacuum wavelength to energy per photon.
Photon energy E = hν = hc/λ, where h = 6.62607015 × 10⁻³⁴ J·s and c = 299792458 m/s are exact SI constants. Convert nanometers to meters by multiplying by 10⁻⁹. Frequency ν = c/λ; divide energy in joules by 1.602176634 × 10⁻¹⁹ J/eV to obtain electronvolts. A vacuum wavelength of 500 nm gives approximately 3.97289 × 10⁻¹⁹ J, 2.47968 eV, and 5.99585 × 10¹⁴ Hz. This is energy for one photon, not beam power or total pulse energy. Use vacuum wavelength: wavelength in a material depends on its refractive index. Inputs from 1e-12 to 1e20 nm are supported, with output rounded to 12 significant digits. The broad range is mathematical and does not imply that every wavelength is practical to produce or measure. All calculations stay on your device.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What is the photon energy formula?
E = hc/λ = hν. Use vacuum wavelength in meters with the SI constants h and c. This calculator accepts nanometers and converts them to meters.
What is the photon energy at 500 nm?
Approximately 3.97289 × 10⁻¹⁹ joules or 2.47968 electronvolts per photon, with frequency 5.99585 × 10¹⁴ Hz.
Does shorter wavelength mean more energy?
Yes. Energy per photon is inversely proportional to vacuum wavelength: halving wavelength doubles photon energy.
Can I enter the wavelength measured inside glass or water?
Convert it to vacuum wavelength first using the refractive index at that frequency. This tool assumes vacuum wavelength and uses the speed of light in vacuum.
Is photon energy the same as laser power?
No. Power is energy per unit time. Total beam energy also depends on the number of photons; wavelength alone determines energy per photon.
Are values sent to a server?
No. Calculations run locally in your browser. Copy copies the results; Reset restores the 500 nm example.