# Reduced Planck Constant Constant

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

## reducedPlanckConstant

Reduced Planck constant

Try it yourself:

```calculio
reducedPlanckConstant
```

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## Reduced Planck constant: h-bar

**reducedPlanckConstant**, ℏ, equals Planck constant divided by 2π. It is the standard quantum constant for angular momentum and angular frequency.

## Practical use

Use ℏ in E = ℏω and quantum commutation relations. Compare [planckConstant](https://calcul.io/constants/planckConstant/index.md) for ordinary frequency and [tau](https://calcul.io/constants/tau/index.md) for the full-turn factor 2π.

## Caveats

Do not mix ω with frequency ν: they differ by 2π. Use [multiply](https://calcul.io/function/multiply/index.md) with units of radians per second, and retain the distinction in symbolic work with [simplify](https://calcul.io/function/simplify/index.md).

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