Password Strength Checker helps you evaluate password security. Enter a password to instantly see strength level, information entropy, and estimated crack time. The tool checks multiple factors including password length, character complexity, and common weak patterns, providing improvement suggestions. All analysis happens locally in your browser - passwords never leave your device.
Understanding Password Entropy
Information entropy measures password randomness in bits. Higher entropy means harder to crack. General guidelines: 40-60 bits is weak, 60-80 bits is moderate, 80+ bits is strong. This tool calculates theoretical entropy based on character set size and password length.
How Crack Time is Estimated
- Assumes attacker can try 10 billion guesses per second (professional hardware)
- Calculates all possible combinations from the character set
- On average, half the combinations need to be tried
- Converts to human-readable time units (seconds/minutes/years)
Secure Password Guidelines
Strong passwords should: be 12+ characters long, mix uppercase and lowercase letters, include numbers and special symbols, avoid personal info (birthdays, names), avoid common words or keyboard patterns, be unique for each account.
FAQ
Q: Is my password uploaded anywhere?
A: No. All password analysis happens locally in your browser. Passwords are never transmitted over the network. This is a design principle ensuring your password safety.
Q: Why do same-length passwords have different strengths?
A: Password strength depends not just on length but character diversity. A 12-character password using uppercase+lowercase+numbers+symbols is harder to crack than a 20-character lowercase-only password because the character set is larger.
Q: Is the crack time accurate?
A: Crack time is a theoretical estimate based on brute-force worst case. In practice, if passwords contain common words or patterns, dictionary attacks may crack them faster. That's why you should avoid predictable passwords.