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Password Entropy Calculator

Bits of entropy as length times log2 of the alphabet size.

 

 

Bits

About this calculator

Use this calculator to sketch the entropy of a random string drawn uniformly from a known alphabet. Enter character length and how many symbols you actually sample from.

Bits = length × log2(alphabet size). 12 characters from 62 symbols is about 71.5 bits if every symbol is equally likely. Humans are not random; dictionary words collapse this number. This is not a password-strength meter of a real passphrase.

Length: How many characters.

Alphabet size: How many symbols you actually sample from.

Bits: Estimated Shannon entropy for a uniform draw.