Password Strength Checker
Check how strong your password is
Calculator
Your password is checked locally and never sent to any server.
Password Security
Learn what makes a password strong
A strong password protects your accounts from unauthorized access. Our checker analyzes:
- Length and character variety
- Entropy (randomness measurement)
- Common password databases
- Keyboard patterns and sequences
- Dictionary words
How to Use
Check how strong your password is
Enter password
Type or paste the password you want to check in the input field
View strength meter
See the visual strength bar and score from Very Weak to Very Strong
Check criteria
Review which security criteria your password meets or fails
Follow suggestions
Use the improvement suggestions to make your password stronger
Password Entropy Formula
Entropy (bits) = Length x log2(CharacterSetSize)
Entropy measures password randomness. Character set: lowercase (26), uppercase (26), digits (10), symbols (32). A 12-char password with all types has ~79 bits of entropy. 60+ bits is considered strong against modern attacks.
Frequently Asked Questions
A strong password has: 12+ characters, mix of uppercase and lowercase letters, numbers, and special characters (!@#$%^&*). It should not be a common word, contain personal information, or follow predictable patterns like "123456" or "qwerty". The longer and more random, the stronger.
Password strength is calculated using entropy - a measure of randomness. Entropy = password length x log2(character set size). A 12-character password using all character types (94 possible) has about 79 bits of entropy. We also check against common password lists and patterns.
Crack time depends on password entropy and attacker resources. A modern GPU cluster can try 10 billion passwords per second. An 8-character lowercase password (26^8) takes seconds. A 16-character mixed password can take millions of years. Our calculator shows estimated crack times.
Yes, reputable password managers (1Password, Bitwarden, LastPass) are very safe. They use strong encryption (AES-256) and zero-knowledge architecture. Using a password manager with unique, strong passwords for each site is much safer than reusing passwords or using weak ones.
Top passwords to avoid: 123456, password, qwerty, abc123, letmein, monkey, dragon, baseball, iloveyou, trustno1, sunshine, master, welcome, shadow. Also avoid your name, birthday, phone number, or any personal information that could be guessed or found online.
Your password is checked 100% locally in your browser using JavaScript. It is never sent to any server or stored anywhere. This is the safest way to check password strength. You can verify this by checking the network tab in your browser developer tools.
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