# Wien Displacement Constant

Use Wien Displacement in Calcul.io. See what this built-in constant represents, enter it in an editable calculation, and review related values and units.

## wienDisplacement

Wien displacement law constant

Try it yourself:

```calculio
wienDisplacement
```

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## Wien displacement constant for blackbody peaks

**wienDisplacement** is the constant in Wien’s displacement law: a blackbody’s peak wavelength times its absolute temperature is constant.

## Practical use

Estimate peak wavelength with λmax = b/T, or infer a temperature from a measured peak. Pair it with [secondRadiation](https://calcul.io/constants/secondRadiation/index.md) for full Planck-law work and [stefanBoltzmann](https://calcul.io/constants/stefanBoltzmann/index.md) for total radiated power.

## Caveats

The peak depends on whether the spectrum is plotted per wavelength or per frequency; their maxima differ. Use kelvin and metres consistently, and use [divide](https://calcul.io/function/divide/index.md) for the conversion. Real emitters can depart from ideal-blackbody behavior.

[All constants](https://calcul.io/constants/index.md)