Password Strength Tester
Real-time analysis with NIST & OWASP compliance checking, entropy calculation, crack time estimation, and breach database verification
How Password Strength Is Calculated
Password strength is determined by multiple factors working together. Our calculator analyzes entropy (mathematical randomness), character diversity (mix of character types), length, and checks for known patterns and compromised passwords.
A password with high entropy but using a common word offers less protection than a random passphrase. That's why we combine mathematical analysis with real-world breach data to give you an accurate security assessment.
Understanding Entropy
Entropy measures password unpredictability in bits. Each bit doubles the number of possible combinations. A password with 40 bits of entropy has 2^40 (about 1 trillion) possible combinations.
NIST vs OWASP Password Guidelines
NIST SP 800-63B
- Minimum 8 characters (12+ recommended)
- No arbitrary complexity rules
- Check against breached passwords
- No forced periodic changes
- Allow all printable characters
OWASP ASVS 4.0
- Minimum 12 characters
- Maximum 128 characters
- Allow all Unicode characters
- Check against top 10K passwords
- Implement rate limiting
Tips for Creating Strong Passwords
Do
- • Use 16+ characters when possible
- • Consider passphrases (random words)
- • Use a password manager
- • Use unique passwords per account
- • Enable 2FA whenever available
Don't
- • Use personal information
- • Use dictionary words alone
- • Use simple substitutions (p@ssw0rd)
- • Reuse passwords across sites
- • Share passwords via email/chat