Password Strength Checker
How strong is your password? This calculator measures password strength by computing entropy (randomness in bits) based on the character set used and password length. It estimates how long a brute-force attack would take with modern GPU hardware doing 10 billion guesses per second.
Password strength depends primarily on two factors:
- Length: The most important factor. Each additional character multiplies the search space.
- Character set size: Using lowercase, uppercase, numbers, and symbols increases possible combinations.
Recommendations:
- Use at least 12 characters (16+ for sensitive accounts)
- Mix character types: uppercase, lowercase, numbers, symbols
- A long passphrase of 4-5 random words is very strong and memorable
- Never reuse passwords across accounts
- Use a password manager to generate and store unique passwords
Entropy reference: 40 bits = moderate, 60 bits = strong, 80+ bits = very strong, 128+ bits = practically uncrackable.