Password Entropy Calculator
Compare the theoretical randomness of generated character passwords and randomly selected word passphrases. No password needs to be entered.
Random character passwords
Theoretical entropy
104.9 bits
Formula: length × log₂(character pool size). Pool: 94 characters.
Randomly chosen word passphrases
Theoretical entropy
55.0 bits
Formula: word count × log₂(word list size).
How to interpret the result
Entropy is measured in bits. Each additional bit doubles the number of possible outcomes if choices are truly independent and uniformly random. This calculator models a generator, not a human-created password.
For example, 16 independent characters selected uniformly from 26 lowercase letters have 16 × log₂(26), or approximately 75.2 bits of entropy. Five independently selected words from a 2,048-word list have 55 bits. Those numbers describe the selection process—not how hard every password would be to crack in real life.
Important limitations
Human choices, common substitutions, repeated patterns, biased random number generators, compromised devices, phishing, and password reuse can all undermine security. This calculator cannot estimate breach exposure, server-side defenses, or actual attack costs. Do not treat its output as a cracking-time guarantee.
Learn what entropy means, compare passwords and passphrases, or generate a new password.