Frequency to Energy Converter
Calculate the photon energy at any frequency using Planck's relation E = hf. Output in electron-volts (auto-scaled µeV → GeV), joules, and kJ/mol. Includes EM-spectrum band classification and an ionizing-radiation indicator (above 13.6 eV).
Input
Result
Photon Energies Across the EM Spectrum
| Source | Frequency | Wavelength | Photon Energy | Band |
|---|---|---|---|---|
| AM radio (mid) | 1 MHz | ~300 m | 4.14 neV | Radio |
| FM radio (mid) | 100 MHz | ~3 m | 414 neV | Radio |
| WiFi 2.4 GHz | 2.4 GHz | ~12.5 cm | 9.93 µeV | Microwave |
| Microwave oven | 2.45 GHz | ~12.2 cm | 10.1 µeV | Microwave |
| Far IR | 1 THz | 300 µm | 4.14 meV | Infrared |
| Near IR | 300 THz | 1,000 nm | 1.24 eV | Infrared |
| Red light | 430 THz | 697 nm | 1.78 eV | Visible |
| Green light | 540 THz | 555 nm | 2.23 eV | Visible |
| Violet light | 750 THz | 400 nm | 3.10 eV | Visible |
| UV-A | ~900 THz | ~333 nm | ~3.72 eV | UV (non-ionizing) |
| UV-C (germicidal) | 1 PHz | 300 nm | 4.14 eV | UV |
| Hydrogen ionization | 3.29 PHz | 91.2 nm | 13.6 eV | UV (threshold) |
| Soft X-ray | 100 PHz | 3 nm | 414 eV | X-ray |
| Hard X-ray | 10 EHz | 30 pm | 41.4 keV | X-ray / Gamma |
| Cobalt-60 gamma | ~283 EHz | ~1.06 pm | 1.17 MeV | Gamma |
About Photon Energy & Planck's Relation
Light comes in discrete packets called photons, each carrying energy proportional to its frequency. Max Planck's 1900 relation E = hf (where h is Planck's constant) made this quantization explicit and launched quantum mechanics. This tool computes a single photon's energy at any frequency from radio (~10⁻⁹ eV) to gamma (~10⁶ eV) — a span of 15 orders of magnitude.
Why three energy units (eV, J, kJ/mol)?
Electron-volts (eV) are the most intuitive unit for photons because they map directly to atomic phenomena — visible light photons are ~1.5–3 eV (matches electronic transitions), UV-C is ~4–10 eV (breaks bonds), 13.6 eV ionizes hydrogen. Joules are SI energy. kJ/mol matters in chemistry — multiplying a single photon's energy by Avogadro's number gives the energy of one mole of those photons, the meaningful quantity for bulk reactions like photosynthesis (~180 kJ/mol per red photon × ~6 × 10²³ = ~600 kJ/mol absorbed).
The 13.6 eV ionizing threshold
Photons with energy ≥ 13.6 eV can ionize hydrogen atoms (knock the electron out). This corresponds to ~3.3 PHz (91 nm wavelength), deep in the UV. Below 13.6 eV is "non-ionizing" radiation (visible light, IR, microwaves, radio) — energetically incapable of breaking molecular bonds directly. Above is "ionizing" (UV-C, X-ray, gamma) — biologically damaging because individual photons carry enough energy to break DNA.
Energy → photon count conversion
A 60-watt light bulb (60 J/s) emitting 600 nm green light (2 eV = 3.2 × 10⁻¹⁹ J per photon) emits about 60 / 3.2 × 10⁻¹⁹ = 1.9 × 10²⁰ photons per second. The discreteness only becomes practically observable at very low intensities or for highly energetic photons.