Enter any wavenumber and select its unit below. Instantly view wavelength with smart unit conversions. Export tables, verify formulas, and reuse values confidently anywhere.
| Wavenumber (1/cm) | Wavelength (µm) | Wavelength (nm) |
|---|---|---|
| 1000 | 10.0 | 10000 |
| 1600 | 6.25 | 6250 |
| 4000 | 2.50 | 2500 |
These examples assume the wavenumber definition as the reciprocal of wavelength.
Core relation: wavelength is the reciprocal of wavenumber.
Optional outputs: f = c / λ and E(eV) = (h c) / (λ e).
Wavenumber is the number of wave cycles per unit distance, written as ν̃. In spectroscopy it is usually reported in cm-1 because it keeps typical infrared values compact. Mid‑IR bands often fall near 400–4000 cm-1, and Raman shifts are commonly discussed in the same span.
Many instruments, filters, and optics are specified by wavelength rather than wavenumber. Converting helps you compare an IR peak with detector windows or laser lines. For example, 4000 cm-1 corresponds to 2.5 µm, and 1000 cm-1 corresponds to 10 µm in the thermal‑infrared region.
The calculator first converts your input to reciprocal meters (m-1). The key factor is 1 cm-1 = 100 m-1. Then wavelength in meters is λ = 1/ν̃. Finally, λ is scaled into nm, µm, mm, cm, m, or Å using powers of ten.
Real spectra have finite resolution, so rounding matters. FTIR data may be collected at 1–4 cm-1 resolution. If your peak is 1600 cm-1, the wavelength is 6.25 µm; reporting 6.2500 µm only makes sense when measurement uncertainty is small. Use the significant‑figure control to match data quality.
With extras enabled, frequency comes from f = c/λ using c = 299,792,458 m/s. Photon energy uses E = hc/λ and is shown in eV. A handy reference: 1000 cm-1 gives λ = 10 µm, f ≈ 29.98 THz, and E ≈ 0.124 eV, typical for vibrational transitions.
Wavenumber cannot be zero because λ would be infinite. Negative values are uncommon for physical spectra and may indicate a sign convention or processing artifact. For UV‑visible light, 10,000–50,000 cm-1 maps to about 1000–200 nm. If your result looks off by 10×, recheck units.
CSV output is ideal for spreadsheets, peak lists, and batch documentation. The PDF export creates a single‑page record for lab notebooks or client files, ready for quick secure sharing. Keeping wavenumber, wavelength, and optional frequency/energy together reduces transcription errors and improves traceability when you revisit the spectrum.
No. Wavenumber is cycles per distance (1/length), while frequency is cycles per time (1/time). They relate by f = c·ν̃ when ν̃ is in m-1 and c is the speed of light.
It keeps common infrared values compact and easy to compare. Many reference tables, libraries, and instrument displays are standardized in cm-1, so reporting peaks this way improves consistency across labs.
Use µm for mid‑IR bands, nm for visible and UV work, and Å for atomic‑scale conventions. Pick the unit that matches your instrument specifications or the literature you are comparing against.
The unit conversion is mathematically exact. Practical accuracy depends on your input rounding and instrument calibration. Choose significant figures that reflect spectral resolution to avoid implying precision beyond your measurement.
Yes. Select the correct wavenumber unit in the dropdown. The calculator converts internally to m-1, computes λ, then converts to the output unit you selected.
Because λ = 1/ν̃ would require division by zero, creating an infinite wavelength. In practice, a zero entry usually indicates missing data, a placeholder, or an input mistake.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.