Other Calculators

Password Entropy Calculator

Calculate the entropy (randomness strength) of a password in bits, based on its length and character set.

Character pool size —

Entropy —

Strength rating —

About the Password Entropy Calculator

Password entropy measures how unpredictable a password is, expressed in bits. More bits mean exponentially more possible combinations an attacker would have to try to guess it through brute force.

Formula: Entropy (bits) = Length × log₂(Character Pool Size)

The character pool size is the sum of every character set used: 26 for lowercase, 26 for uppercase, 10 for digits and roughly 32 for common symbols. Longer passwords and larger character pools both increase entropy — length matters more than most people expect.