Photon Energy Calculator
Convert wavelength to photon energy and frequency.
Your numbers
Your results
Energy (eV)
Energy (eV)
—
Energy (J)
—
Frequency (THz)
—
Energy per mole of photons (kJ/mol)
—
Photon Energy Calculator by TheCalcTools
How the Photon Energy Calculator works
Enter the wavelength in nanometres (green light is about 550 nm).
Photon energy is Planck’s constant times frequency, which equals hc divided by the wavelength.
The calculator also gives the energy per mole of photons.
The formula
E = h c ÷ λf = c ÷ λ
Worked example
Using the default values shown in the calculator:
| Wavelength (nm) | 550 |
|---|
- f = c ÷ λ = 545.1 THz.
- E = 1,239.84 ÷ 550 = 2.2543 eV.
- That is 3.612 × 10^-19 J, or 218 kJ per mole of photons.
Result:
| Energy (eV) | 2.2543 |
|---|---|
| Energy (J) | 3.612 × 10^-19 |
| Frequency (THz) | 545.08 |
| Energy per mole of photons (kJ/mol) | 217.50 |
Frequently asked questions
Why does blue light carry more energy than red?
Shorter wavelength means higher frequency, and photon energy is proportional to frequency.
How is eV defined?
One electronvolt is 1.602176634 × 10⁻¹⁹ J, the energy gained by an electron across 1 volt.
Sources and further reading
Related calculators
More in Physics · All calculators
This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.