# 📝How-to: read entropy available

- tags
- #how-to

Entropy is an estimate of the number of bits of entropy in the pool (max 4,096 in linux). If the number is below 200, that’s bad.

```
cat /proc/sys/kernel/random/entropy_avail
```

If entropy is below 160(?) (length of sha-1 hash), reading from `/dev/random`

will block until more entropy is available.

Resources: