---
title: "Blackbody / Wien's Law calculator — AperiOptic"
description: "Peak wavelength & total exitance of a blackbody. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/blackbody-wiens-law"
---

# Blackbody / Wien's Law calculator

Peak wavelength & total exitance of a blackbody.

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

Formula: `λpk = b/T · M = σT⁴`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| Temperature | `T` | K | 5778 |

## Result with the default inputs

- Peak λ: 501.5182 nm
- Exitance: 6.3201e+7 W/m²

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/blackbody-wiens-law?T=5778`](https://aperioptic.com/calculators/blackbody-wiens-law?T=5778). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Wien's displacement law](https://en.wikipedia.org/wiki/Wien%27s_displacement_law)

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

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