Photon Energy Calculator
Calculate the energy of a photon from its wavelength or frequency.
Shows energy in joules and electron volts, and identifies the spectral region.
Photon Energy
A photon is a quantum of electromagnetic radiation. Its energy depends on its frequency (or equivalently, its wavelength):
E = hf = hc/λ
Where:
- E = Photon energy (joules or eV)
- h = Planck’s constant = 6.62607 × 10⁻³⁴ J·s
- f = Frequency (Hz)
- c = Speed of light = 2.998 × 10⁸ m/s
- λ = Wavelength (m)
Unit conversion: 1 eV = 1.602 × 10⁻¹⁹ J
Electromagnetic spectrum reference:
| Region | Wavelength | Energy per photon |
|---|---|---|
| Radio | > 1 mm | < 0.00124 eV |
| Microwave | 1 mm – 1 m | 0.00124 – 1.24 meV |
| Infrared | 700 nm – 1 mm | 1.24 meV – 1.77 eV |
| Visible (red) | 700 nm | 1.77 eV |
| Visible (violet) | 400 nm | 3.10 eV |
| UV | 10 – 400 nm | 3.1 – 124 eV |
| X-rays | 0.01 – 10 nm | 124 eV – 124 keV |
| Gamma rays | < 0.01 nm | > 124 keV |
Photon energy is important for:
- Understanding why UV causes sunburn but visible light does not (higher photon energy can break chemical bonds)
- Solar cell design — only photons with enough energy can excite electrons
- Night vision — IR photons carry enough energy to be detected
- X-ray imaging — high-energy photons penetrate tissue
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.