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Password Entropy Calculator

Calculate password and encryption key strength

Number of characters in the password. Longer passwords exponentially increase entropy.
characters
Select which character types are used, or enter a custom charset size. Larger charset = more entropy per character.
chars

Results

Entropybits
Possible Combinations
Time @ 1,000/sec (online)
Time @ 1,000,000/sec (fast)
Time @ 1 billion/sec (GPU)
Time @ 1 trillion/sec (cluster)
Strength Rating
How it works: Entropy = length × log2(charset_size). A 12-character password using 95 printable ASCII chars has ~78.8 bits of entropy. Time to crack = (charset^length / 2) / guesses_per_second. 128+ bits is considered computationally infeasible to brute force.