Light comes in packets called photons whose energy depends only on frequency. Blue photons carry more energy than red ones, which is why UV light causes sunburn and infrared does not.
How to use the Photon Energy Calculator
- Given
- Wavelength λ
- Frequency f
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose wavelength or frequency and enter the value.
Inputs explained
| Field | What to enter |
|---|---|
| Given | Choose one: Wavelength, Frequency |
| Wavelength λ | Units: nm, µm, mm, m, pm, Å |
| Frequency f | Units: THz, GHz, PHz, Hz |
What each result means
- Photon energy in eV = [Photon energy]÷1.602176634e-19
- Energy per mole of photons = [Photon energy]×6.02214076e23÷1000
Example values
How the main result changes when Wavelength λ changes and everything else stays at the example values above:
| Wavelength λ (nm) | Photon energy in eV (eV) |
|---|---|
| 250 | 4.9594 |
| 375 | 3.3062 |
| 500 | 2.4797 |
| 625 | 1.9837 |
| 750 | 1.6531 |
| 1,000 | 1.2398 |
Formula
E = h·f = h·c/λ
Worked example
Inputs: Given: Wavelength; Wavelength λ: 500 nm.
Results: Photon energy = 3.9729e-19 J; Photon energy in eV = 2.479684 eV; Energy per mole of photons = 239.25313 kJ/mol.
Key terms
- Photon
- Quantum of electromagnetic radiation.
Frequently asked questions
What is Planck's constant?
h = 6.62607015 × 10⁻³⁴ J·s (exact).
How much energy does a green photon carry?
About 2.3 eV.
Why does UV damage DNA?
Its photons have enough energy (3–6 eV) to break chemical bonds.
What is an einstein?
One mole of photons.