Photon Energy Calculator
Enter frequency or wavelength to compute photon energy E = h·f = h·c/λ (in joules and eV).
Input Data
Results
At a glance:The energy of a single photon is quantized: E = h·f = h·c/λ, where h = 6.626×10⁻³⁴ J·s, c = 2.998×10⁸ m/s and λ the wavelength (f = c/λ). In electron-volts, E(eV) ≈ 1240/λ(nm) — a handy rule: a 500 nm photon has ~2.48 eV, visible light spans ~1.8–3.1 eV, UV >3.1 eV, infrared <1.8 eV. Higher frequency/shorter wavelength → higher energy (γ-rays most energetic, radio least). Photon energy sets the threshold for electronic transitions, chemical bonds and the photoelectric effect. This tool returns E in J and eV from f or λ.
Formula
E = h·f = h·c/λ
E(eV) ≈ 1240/λ(nm)
f = c/λ
$$E = h f = \dfrac{h c}{\lambda}$$$$1\,\text{eV} = 1.602 \times 10^{-19}\,\text{J}$$How to Use
- Enter the frequency f (Hz) or wavelength λ (nm).
- The calculator returns E in joules and eV.
Case Studies
Green light
λ = 532 nm.
E = 1240/532 ≈ 2.33 eV ≈ 3.73×10⁻¹⁹ J.
Within the visible range.
FAQ
Why is energy inversely proportional to wavelength?
Because f = c/λ, so E = hc/λ — shorter wavelength means higher frequency and thus higher photon energy.
What is 1240 eV·nm?
h·c expressed in convenient units: E(eV) = hc/λ = 1240 eV·nm / λ(nm). Quick for spectroscopy.
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.