// tool reference · Vulnerability & Assessment
Password Entropy Calculator Free
Measure real password strength in bits — not a coloured bar.
Open Password Entropy Calculator →
What it does
Calculates actual entropy in bits and estimates crack time against realistic attack rates — rather than the meaningless "strong!" meter most sites show.
When to use it
- Setting a password policy; explaining to someone why length beats symbols.
Inputs
Field names are the actual form parameters, verified against source.
| Field | Type | Required | Notes |
|---|---|---|---|
| pw | text | required | The candidate password. |
What you get back
Entropy in bits with crack-time estimates at several attack rates.
How it works
Deterministic entropy calculation. Local — the value is not transmitted or stored.
Privacy
Nothing is stored or logged. Still: do not paste a password you are actively using anywhere.
Standards
NIST SP 800-63B