Password Strength Checker

Our Password Strength Checker analyzes your password's robustness by evaluating its entropy, a measure of randomness and unpredictability. A password built from a common word or pattern can fall to a dictionary attack almost at once. This tool gives an entropy score, a strength rating, two brute-force crack-time estimates and suggestions for improving the password.

The score starts as length × log2(pool), where the pool adds 26 for lowercase, 26 for uppercase, 10 for digits and 33 for symbols, counting only the sets the password uses. It is halved if the password contains a common pattern such as "password", "qwerty" or "123456", multiplied by 0.8 for three identical characters in a row and by 0.8 again for a run such as "123" or "abc". The rating steps up at 28, 36, 60, 80 and 100 bits, from Very Weak to Very Strong. The two crack-time rows take half of 2^score guesses, so the pattern penalties count, at 10 billion and 100 billion guesses per second. Those are speeds for an attacker who has stolen a password database and guesses offline; a live login page that limits failed attempts is far slower to attack.

Many users make the mistake of reusing passwords or using easily guessable combinations like birthdays or common dictionary words. Avoid sequential patterns, keyboard patterns, and personal information that can be found online. Length counts for more than variety: in this checker, 16 random lowercase letters score 75.2 bits, more than 10 characters drawn from all four sets (65.7 bits).