---
title: "Wavelength ↔ Wavenumber calculator — AperiOptic"
description: "Convert between wavelength, frequency and spectroscopic wavenumber. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/wavelength-wavenumber"
---

# Wavelength ↔ Wavenumber calculator

Convert between wavelength, frequency and spectroscopic wavenumber.

Category: [Photonics](https://aperioptic.com/calculators)

Formula: `ν̃ = 1/λ · ν = c/λ`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| λ | `lam` | nm | 532 |

## Result with the default inputs

- Wavenumber: 18796.9925 cm⁻¹
- Frequency: 563.5197 THz

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/wavelength-wavenumber?lam=532`](https://aperioptic.com/calculators/wavelength-wavenumber?lam=532). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Wavenumber](https://en.wikipedia.org/wiki/Wavenumber)

[All optics calculators](https://aperioptic.com/calculators)

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The interactive page: https://aperioptic.com/calculators/wavelength-wavenumber (AperiOptic runs in the browser; free, no account). Every page of the site as Markdown: https://aperioptic.com/llms.txt