Free Password Strength Checker — Estimate Crack Time
Check how strong your password really is. The tool calculates entropy in bits and estimates the time required to crack it using modern hardware — giving you a clear picture of your password's security. Whether you're choosing a new password or auditing existing ones, this tool shows you exactly where you stand.
How Strength Is Measured
The checker analyses character diversity (lowercase, uppercase, digits, symbols) and length to compute Shannon entropy — a measure of randomness in bits. It then divides the total keyspace by a realistic offline attack rate (10 billion guesses/second, typical for modern GPU clusters) to estimate crack time — from "instantly" to "centuries."
Strength Rating Scale
What Affects Password Strength?
- → Length — the single most important factor. Each additional character multiplies the keyspace.
- → Character diversity — mixing uppercase, lowercase, digits, and symbols increases entropy per character.
- → Unpredictability — random passwords are far stronger than dictionary words or patterns.
- → Unique characters — passwords with repeated characters have lower entropy.
Tips for Stronger Passwords
- 1. Aim for 16+ characters — this pushes crack time into centuries even for determined attackers.
- 2. Use a password manager to generate and store unique passwords for every account.
- 3. Enable two-factor authentication (2FA) as an additional security layer.
- 4. Never reuse passwords — one breach can compromise multiple accounts.
100% private — your password never leaves your browser. No registration, no logging, no tracking.