Light comes in packets called photons. Shorter wavelengths, such as ultraviolet, carry more energy per photon.
How to use the Photon Energy Calculator
- Wavelength
- Want to work backwards? Type a value into Photon energy and Wavelength is calculated for you.
Results update as you type, and every field accepts the units shown in its menu.
How it works
Multiply Planck’s constant by the speed of light and divide by the wavelength.
What each result means
- Photon energy = 6.62607015[Photon energy]-34 × 299792458 ÷ [Wavelength]
- Energy in electronvolts = [Photon energy] ÷ 1.602176634[Photon energy]-19
- Frequency = 299792458 ÷ [Wavelength]
Example values
How the main result changes when Wavelength changes and everything else stays at the example values above:
| Wavelength (nm) | Photon energy (J) |
|---|---|
| 275 | 7.2234e-19 |
| 412.5 | 4.8156e-19 |
| 550 | 3.6117e-19 |
| 687.5 | 2.8894e-19 |
| 825 | 2.4078e-19 |
| 1,100 | 1.8059e-19 |
Formula
E = h c ÷ λWorked example
Inputs — Wavelength: 550 nm.
Results — Photon energy = 3.6117e-19 J; Energy in electronvolts = 2.2543 eV; Frequency = 545,077,196,363,636.3 Hz.
Frequently asked questions
What is an electronvolt?
The energy an electron gains crossing 1 volt: 1.602 × 10⁻¹⁹ J.
Why can UV cause sunburn but radio waves cannot?
UV photons carry enough energy to damage molecules.
What formula does the Photon Energy Calculator use?
E = h c ÷ λ.
Can I work backwards from the result?
Yes. Type the result you want into Photon energy and the calculator finds the matching wavelength.