Type a password to instantly see its entropy, estimated crack time, and a full character-type breakdown. Everything runs in your browser —your password is never sent anywhere.
Password Strength Checker evaluates a password by computing its Shannon entropy based on character set size and length, then estimates the time needed to brute-force it at 1 billion guesses per second. It also runs 8 specific checks —length, character types, common sequences, repetition, and dictionary patterns —and suggests improvements.
Entropy measures unpredictability in bits. It is calculated as length × log₀charset size). A password using 94 printable ASCII characters with length 12 has about 78.8 bits of entropy —generally considered strong.
The tool assumes an offline brute-force attack at 1 billion guesses per second. This represents a capable attacker with modern hardware. Real crack times vary based on the attack method and attacker resources.
No. All analysis runs entirely in your browser using JavaScript. Your password never leaves your device.
Length is the single most important factor. A 16-character password with mixed characters is far stronger than an 8-character one. Also avoid dictionary words, sequences like "123", and repeated characters.