Password Strength Checker
Test how strong your password is — scores length, complexity and entropy. Free, private.
🔒 Security Tools
Free
Browser-based
—
At least 12 characters
Uppercase letter (A–Z)
Lowercase letter (a–z)
Number (0–9)
Special character (!@#$…)
Not a common pattern or dictionary word
What Each Strength Level Means
| Rating | Entropy | Time to crack (offline) | When to use |
|---|---|---|---|
| Very Weak | < 28 bits | Seconds | Never |
| Weak | 28–35 bits | Minutes to hours | Temporary access only |
| Fair | 36–59 bits | Days to weeks | Low-value accounts |
| Strong | 60–79 bits | Years | Most accounts |
| Very Strong | 80+ bits | Centuries | Email, banking, critical accounts |
Why Password Entropy Matters
Entropy is calculated from the character set size and password length: bits = log₂(charset_size ^ length). A password using only lowercase letters has a charset of 26, while one using all four character classes has a charset of ~95 — producing far more possible combinations per character added.
Tips for Building a Stronger Password
Use a passphrase: four or more random words strung together (e.g., "correct-horse-battery-staple") are both memorable and highly secure. Avoid substitutions like "p@ssw0rd" — crackers test those variations first. Use a password manager to generate and store truly random passwords without having to memorise them.