Password Entropy Calculator
How much real randomness a password has, and how long it survives.
Only meaningful for genuinely random passwords. Anything based on a word, name or pattern is far weaker than the figure shown.
How it works
Entropy is length x log2(charset size), measured in bits. Each extra bit doubles the search space.
The critical caveat: this assumes the password was generated randomly. "P@ssw0rd1" scores 59 bits by this formula and is cracked instantly, because an attacker guesses dictionary words with substitutions long before brute force. The number above is an upper bound on strength, not a measurement of it.
Length beats complexity. Adding one character to a 62-character set multiplies the space by 62; adding symbols to a fixed length multiplies it by roughly 1.5 per character.
Common questions
How many bits is enough?
Under 50 is weak, 60-80 is reasonable for most accounts with rate limiting, and 100+ is appropriate for anything protecting other credentials. A random four-word passphrase from a large list lands near 52; five words near 65.