Password Entropy Calculator

Calculate password strength and estimated crack time based on entropy analysis.

About Password Entropy

What It Measures

Entropy quantifies password randomness and unpredictability using information theory.

How It's Calculated

H = L × log₂(N), where L is password length and N is the character pool size.

Why It Matters

Higher entropy means more possible combinations, making brute-force attacks harder.

Your password is never sent to any server. All calculations happen locally in your browser.

Try Sample Passwords

Security Recommendations

Best Practices

  • Use a unique password for each account
  • Consider using a password manager
  • Enable two-factor authentication (2FA) when available
  • Avoid common words, phrases, or patterns
  • Don't include personal information (birthdays, names, etc.)
  • Change passwords if a service reports a breach

Entropy Guidelines

< 28 bits: Very Weak (crackable instantly)
28-35 bits: Weak (hours to days)
36-59 bits: Fair (months to years)
60-127 bits: Strong (decades)
128+ bits: Very Strong (uncrackable)