# LN2 Constant

Use LN2 in Calcul.io. See what this built-in constant represents, enter it in an editable calculation, and review related values and units.

## LN2

Try it yourself:

```calculio
LN2
log(2)
```

---

## LN2: natural logarithm of two

**LN2** is ln(2), approximately 0.693147. It appears in half-life, information, and exponential-growth formulas.

## Typical use

A half-life relation often uses LN2 divided by a decay constant. Pair it with [log()](https://calcul.io/function/log/index.md), [exp()](https://calcul.io/function/exp/index.md), and [division](https://calcul.io/function/divide/index.md) when rearranging exponential models.

## Caveat

Use consistent time units in decay calculations and avoid rounding LN2 early.

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