Wavelength ⇄ Frequency ⇄ Energy Converter

Convert any one of wavelength λ, frequency ν, photon energy E, or wavenumber ν̃ into the other three — anywhere on the electromagnetic spectrum from extra-long-wave radio (10 000 km) to TeV gamma rays. Edit any field and watch the rest snap; the spectrum bar highlights the active band; visible light shows its approximate sRGB colour. Uses c = 299 792 458 m/s in vacuum and the 2019 SI-exact values of h, hc, e. Pure browser — no network.

1. Convert

Wavelength λ (vacuum)

λ = c / ν

Frequency ν

ν = c / λ

Photon energy E

E = h ν = h c / λ

Wavenumber ν̃ = 1/λ

spectroscopy "kayser"

2. Identified band

Band

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Sub-band

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3. Cross-readout (all units)

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λ (engineering)

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E (J)

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E (eV)

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Wavenumber

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Period (1/ν)

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Photon momentum p = h/λ

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Temperature (E/k_B)

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photon-energy temperature

Wien displacement T_peak

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if λ = b/T, b = 2.898 mm·K

4. Reference photon energies

Source	λ	ν	E

Constants & formulas

Speed of light: c = 299 792 458 m/s (exact). Planck: h = 6.626 070 15 × 10⁻³⁴ J·s (exact). Elementary charge: e = 1.602 176 634 × 10⁻¹⁹ C (exact). hc: 1.986 446 × 10⁻²⁵ J·m = 1239.841 984 eV·nm.

Relations: λ·ν = c · E = h·ν = h·c/λ · ν̃ = 1/λ · E[eV] = 1239.84 / λ[nm] · ν[THz] · λ[µm] = 299.792.

Boltzmann: k_B = 1.380 649 × 10⁻²³ J/K. Wien constant: b = 2.897 771 955 × 10⁻³ m·K. Black-body peak wavelength: λ_peak·T = b. Indices of refraction are 1 (vacuum); divide λ by n to get wavelength in a medium.