Wavenumber Converter
Convert wavelength, wavenumber, frequency, and energy with presets, sliders, and range sweeps.
Range (cm⁻¹)
2500.0 — 25000.0
Energy Range (eV)
0.3100 — 3.0996
Wavenumber
10000.00 cm⁻¹
Freq: 299.792 THz | Energy: 1.23984 eV
ν̃ (cm⁻¹) = 10⁷ / λ (nm)
E (eV) = hc/(eλ) = 1239.842 / λ (nm)
f (Hz) = c/λ = 2.99792458 × 10¹⁷ / λ (nm)
Wavelengths are vacuum values; c, h and e are exact in the SI, so the conversions are exact. A wavelength read in air is shorter by n_air ≈ 1.00027 (visible), so its wavenumber is about 0.03 % higher than the vacuum one.
Wavelength relationships
- Wavenumber (cm⁻¹)
- Energy (eV)
Model and references
Exact. The equations are exact within the stated assumptions, or are a standard's tabulated values. The results are as good as the inputs. About the tiers
Exact relations ν̃ = 1/λ, f = c/λ and E = hc/λ for vacuum wavelengths; c, h and e are exact in the SI. Air wavelengths must be converted to vacuum first.
- BIPM (2019). The International System of Units (SI Brochure), 9th ed. Defining constants c, h and e. bipm.org
- Mohr P. J., Newell D. B., Taylor B. N., Tiesinga E. (2025). CODATA recommended values of the fundamental physical constants: 2022. Rev. Mod. Phys. 97, 025002. doi:10.1103/RevModPhys.97.025002
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