Photon Energy Calculator (Wavelength)
Photon energy calculator: energy of light from its wavelength in eV or J, plus frequency and energy per mole.
E = h cλ
How to use this calculator
- Choose the quantity you want under “Solve for”.
- Type the known values and pick their units: any combination works.
- The result updates as you type. Open “Show the steps” to see the substitution.
E = h·c/λ. Shorter wavelengths carry more energy: UV photons can break chemical bonds, infrared ones cannot.
Formula
E = h cλ
| Symbol | Quantity | Units |
|---|---|---|
| λ | Wavelength | m, km, cm, mm, µm, nm, pm, Å, in, ft, yd, mi, nmi, au, ly |
| E | Photon energy | J, kJ, MJ, cal, kcal, Wh, kWh, eV, BTU, erg, ft·lbf |
Constants used: h = 6.62607015 × 10⁻³⁴ J·s · c = 299792458 m/s
Worked example
Given: λ = 500 nm
E = h cλ
Result: E = 2.47968 eV
Frequently asked questions
Energy of a 500 nm (green) photon?
About 2.48 eV (3.97 × 10⁻¹⁹ J).