# Neutron Mass Constant

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

## neutronMass

Neutron mass

Try it yourself:

```calculio
neutronMass
```

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## Neutron mass

**neutronMass** is the rest mass of a neutron, used in nuclear physics, particle physics, and mass–energy calculations.

## Use

Compare it with [proton mass](https://calcul.io/constants/protonMass/index.md) and [electron mass](https://calcul.io/constants/electronMass/index.md). Convert units with [to()](https://calcul.io/function/to/index.md) and use [multiply()](https://calcul.io/function/multiply/index.md) in energy formulas.

## Caveat

Use rest mass consistently and distinguish a free neutron from a bound nucleus.

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