Password Entropy Calculator

Calculate a password's entropy in bits based on its length and the size of the character set used. Entropy measures how many guesses, on average, a brute-force attacker would need — higher entropy means a stronger password.

Inputs

e.g. 26 lowercase, 52 upper+lower, 62 alphanumeric, 94 all printable ASCII

Results
Entropy
104.9 bits

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Formula

Entropy (bits) = Length × log₂(Character Set Size)

Learn How This Works

Security and API Planning: Entropy, Rate Limits, and Collisions

Password entropy, URL query parameter counting, hash collision probability, and API rate limits — four calculations for planning secure, well-behaved systems.

Frequently Asked Questions

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