Password & Security
Password Strength Checker
Estimate password entropy and time-to-crack in real time.
Enter a password above to see its strength and estimated crack time.
Password & Security
Estimate password entropy and time-to-crack in real time.
Enter a password above to see its strength and estimated crack time.
A password strength checker evaluates how resistant your password is to cracking attacks by analyzing its length, character variety, and pattern predictability. Use this free online tool to test any password before you set it on critical accounts like email, banking, or work systems.
A password strength checker is a security utility that measures password robustness by scoring factors like character count, uppercase/lowercase/number/symbol inclusion, dictionary word detection, and common substitution patterns. The result is a strength rating (weak, fair, good, strong, very strong) and specific feedback on how to improve it.
The checker analyzes your password character-by-character, calculating entropy (the theoretical number of guesses needed to crack it), checking against known weak passwords and keyboard patterns, and identifying reused character types. It then combines these signals into a single strength score: longer passwords with mixed character types score higher, while short, repetitive, or dictionary-based passwords score lower.
| Input | Result | Notes |
|---|---|---|
| password123 | Weak (Entropy: 19 bits) | Common dictionary word + simple number sequence; cracks in minutes |
| Tr0pic@lS1nset2024 | Strong (Entropy: 68 bits) | 18 characters, mixed case, numbers, symbols, no dictionary words; ~4,000+ years to crack |
| xK$9pL2mQ@wR | Strong (Entropy: 72 bits) | 12 random characters, high entropy, unpredictable; impractical to crack |
Entropy is the number of bits of randomness in your password. A 50-bit entropy password requires 2^50 guesses on average to crack; a 72-bit password requires 2^72 guesses, which is impractical even with fast computers.
It's based on the word 'password' (dictionary), uses predictable substitutions (@ for 'a', 0 for 'o'), and is only 10 characters. AI-powered crackers and rule-based attacks exploit these patterns faster than brute force.
No. The checker runs entirely in your browser; your password never leaves your device and is never sent to FreeTools servers. You can disconnect from the internet and the tool still works.
A strong password (60+ bits entropy, 12+ mixed characters) would take a modern computer billions of years to crack by brute force. Real attacks succeed faster via phishing, reuse, or poor account security—so use unique passwords and two-factor authentication.
No. Use a unique strong password for each account. If one site is breached, attackers can test that password on others. Use a password manager (1Password, Bitwarden, KeePass) to generate and store different passwords securely.
Length is the biggest factor (each extra character multiplies entropy by ~5). After 12+ characters, adding symbols, uppercase, numbers, and lowercase in random combinations provides diminishing returns but still helps against specialized attacks.