Password Strength Calculator

About this calculator

A password's entropy measures how many bits of randomness it contains, calculated as the length of the password multiplied by log₂ of the size of the character set it draws from — a longer password, or one drawn from a larger pool of possible characters (lowercase, uppercase, digits, symbols), has higher entropy and more possible combinations an attacker would need to try. The estimated brute-force crack time then comes from dividing the total number of possible combinations (2 raised to the entropy in bits) by an assumed number of guesses per second.

Security teams, IT administrators and anyone designing a password policy use entropy and crack-time estimates to explain why ‘P@ssw0rd1’ is weak despite looking complex — its character set is guessable and it is short — while a longer passphrase built from unrelated words can have far higher entropy despite looking simpler, an approach reflected in modern password guidance such as NIST's SP 800-63B, which now emphasizes length over forced complexity rules.

Type a password and the calculator estimates its entropy in bits, assigns a strength rating, and gives an estimated time to crack it by brute force.