How are wavelength and frequency related?

They are linked by the wave equation c = λ·f, where c is the speed of light (about 2.998×10⁸ m/s in vacuum), λ the wavelength, and f the frequency. Because c is constant, longer wavelengths mean lower frequencies and vice versa — they are inversely proportional.

How is photon energy calculated?

Photon energy follows the Planck relation E = h·f, equivalently E = h·c/λ, where h is Planck's constant (6.626×10⁻³⁴ J·s). Shorter wavelengths carry more energy per photon, which is why ultraviolet, X-rays, and gamma rays are ionising while radio waves are not.

What are the main spectrum bands?

From longest to shortest wavelength: radio, microwave, infrared, visible light, ultraviolet, X-rays, and gamma rays. They form a continuous spectrum; the boundaries are conventions rather than sharp lines, and adjacent bands overlap in practice.

Why is visible light such a tiny part of the spectrum?

Visible light spans only about 400 to 700 nanometres, a narrow slice between infrared and ultraviolet. Human eyes evolved to detect the wavelengths the Sun emits most strongly and that pass through the atmosphere and water, which is a very small fraction of the full range.

Are the band boundaries exact?

No. The divisions are conventional and vary slightly between sources, and neighbouring bands overlap — for example, the line between far-infrared and microwave, or between hard X-rays and gamma rays, is defined more by how the radiation is produced than by a precise wavelength.

What is the Electromagnetic Spectrum Reference?

Complete electromagnetic spectrum from radio waves through gamma rays, with wavelength and frequency ranges for each band plus a converter that links wavelength, frequency, and photon energy. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Electromagnetic Spectrum Reference

Name: Electromagnetic Spectrum Reference
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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The electromagnetic spectrum is a single continuum of radiation, from kilometre-long radio waves to gamma rays smaller than an atomic nucleus. This reference lists every band with its wavelength and frequency range and includes a converter that links wavelength, frequency, and photon energy.

How it works

All electromagnetic radiation travels at the speed of light in vacuum, so wavelength and frequency are tied together by the wave equation:

c = λ · f

where c ≈ 2.998×10⁸ m/s. Rearranging gives f = c/λ. The energy carried by a single photon comes from the Planck relation:

E = h · f = h · c / λ

with Planck’s constant h = 6.626×10⁻³⁴ J·s. Dividing by 1.602×10⁻¹⁹ converts joules to electronvolts. Enter any wavelength or frequency and the tool computes all three quantities and identifies the band.

The bands from long to short wavelength

Band	Wavelength range	Frequency range	Typical sources
Radio	> 1 mm	< 300 GHz	Broadcasting, radar, MRI
Microwave	1 mm – 1 m	300 MHz – 300 GHz	Wi-Fi, microwave ovens, satellite
Infrared	700 nm – 1 mm	300 GHz – 430 THz	Heat lamps, remote controls, thermal imaging
Visible	400 – 700 nm	430 – 750 THz	Sunlight, LEDs, lasers
Ultraviolet	10 – 400 nm	750 THz – 30 PHz	Sun’s UV, germicidal lamps
X-rays	0.01 – 10 nm	30 PHz – 30 EHz	Medical imaging, security scanning
Gamma rays	< 0.01 nm	> 30 EHz	Radioactive decay, nuclear reactions

As wavelength shortens, frequency and photon energy rise. Photons become energetic enough to ionise atoms above roughly 10 eV, which is why UV, X-rays, and gamma rays are hazardous in a way that radio and microwaves are not.

Worked conversions

Green light at 550 nm:

Frequency: c / 550×10⁻⁹ ≈ 5.45×10¹⁴ Hz (545 THz)
Photon energy: h·f ≈ 3.61×10⁻¹⁹ J ≈ 2.25 eV — in the visible band

2.45 GHz microwave oven:

Wavelength: c / 2.45×10⁹ ≈ 0.122 m (about 12 cm)
Photon energy: about 0.000010 eV — far below ionisation, which is why microwave exposure at normal intensities does not damage DNA

Why band boundaries are conventions

The spectrum is physically continuous. The divisions between named bands reflect how radiation is produced and detected, not a discrete jump in physics. For example, hard X-rays and gamma rays overlap in wavelength; the distinction is usually based on origin (atomic transitions vs nuclear transitions). The same is true at the microwave-to-infrared boundary. Treat all stated ranges as useful approximations rather than precise demarcations.