# Phi Constant

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

## phi

Try it yourself:

```calculio
phi
```

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## phi: the golden ratio

**phi** is the golden ratio, (1 + √5)/2, approximately 1.618034. It occurs in algebraic identities, geometry, and some recursive sequences.

## Use

Use [sqrt()](https://calcul.io/function/sqrt/index.md) to construct its exact form and [pow()](https://calcul.io/function/pow/index.md) in its identities. Compare it to [pi](https://calcul.io/constants/pi/index.md) as another important dimensionless constant, and use [numeric()](https://calcul.io/function/numeric/index.md) for decimals.

## Caveat

Its aesthetic reputation does not make it a universal design rule; use it where the mathematics actually applies.

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