EM Spectrum Calculator
Convert between wavelength, frequency, and photon energy across the whole electromagnetic spectrum, with a visual band chart and true visible-light colour.
Visible band
λ = 5.5000 × 10^-7 m · f = 5.4508 × 10^+14 Hz · E = 2.25426 eV
One wave, three numbers
Every electromagnetic wave can be described by its wavelength (λ), frequency (f), or the energy of one photon (E). They are not independent — fix one and the other two follow:
c = λ · f and E = h · f = h·c / λ, where c ≈ 2.998 × 10⁸ m/s is the speed of light and h is Planck's constant. A handy shortcut for light: E(eV) ≈ 1239.84 / λ(nm).
Bands of the spectrum
| Band | Wavelength | Typical use |
|---|---|---|
| Radio | > 1 m | Broadcast, Wi-Fi, radar |
| Microwave | 1 m – 1 mm | Ovens, 5G, satellite |
| Infrared | 1 mm – 750 nm | Thermal imaging, remotes |
| Visible | 750 – 380 nm | Human vision, displays |
| Ultraviolet | 380 – 10 nm | Sterilisation, sunburn |
| X-ray | 10 – 0.01 nm | Medical imaging |
| Gamma | < 0.01 nm | Nuclear, radiotherapy |
Why higher frequency means higher energy
Because energy scales directly with frequency, a gamma photon carries billions of times more energy than a radio photon. That single fact explains the spectrum's behaviour: low-energy radio and microwaves pass harmlessly through tissue, visible light is energetic enough to drive vision and photosynthesis, and UV/X-ray/gamma photons carry enough energy to break chemical bonds and ionise atoms — which is why they are called ionising radiation.
The visible window
Human eyes respond to a thin slice from about 380 nm (violet) to 750 nm (red) — under a single octave of frequency, yet it contains every colour we can see. Inside that range this tool renders the approximate true colour of the wavelength; outside it, the photon exists but simply has no colour to the eye.