# Fine Structure Constant

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

## fineStructure

Fine-structure constant

Try it yourself:

```calculio
fineStructure
```

---

## Fine-Structure Constant

**fineStructure** is a dimensionless constant measuring the strength of electromagnetic interaction.

## Dimensionless physics

It links [elementaryCharge](https://calcul.io/constants/elementaryCharge/index.md), [planckConstant](https://calcul.io/constants/planckConstant/index.md), and [speedOfLight](https://calcul.io/constants/speedOfLight/index.md). Because it is dimensionless, it is especially useful for comparing physical regimes.

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