How fast could your password
be cracked?
Type any password below to see how long it would take an attacker to crack it,
and what you can do to make it stronger.
Entropy is a measure of how unpredictable your password is - how many different guesses an attacker would need to make before they could find it. Each “bit” of entropy doubles the number of possible passwords. So a password with 10 bits has 1,024 possible combinations, while one with 40 bits has over a trillion.
Importantly, entropy only reflects true randomness. Repeating a character 16 times doesn’t give you 16 characters worth of entropy - an attacker knows to try that pattern immediately. That’s why this tool calculates effective entropy, which penalises predictable patterns like repetition, sequences, and keyboard walks.
The formula is: entropy = log₂(possible characters ^ password length). For example, a lowercase-only 8-character password uses a pool of 26 characters: 26⁸ = 208 billion combinations = about 38 bits. Adding uppercase, numbers, and symbols grows the pool to 94 characters: 94⁸ = about 52 bits. Going from 8 to 16 characters doubles the exponent, jumping that to 105 bits - length matters far more than complexity alone.