Password Entropy Calculator
Works out entropy from a password’s length and the size of its character set.
Password entropy
— bits
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
Character set size —
Bits per character —
Possible passwords —
Passphrase entropy — bits
Reading this —
The formula
entropy = length × log₂(set size)
Each extra bit doubles the number of possibilities.
What to watch out for
Adding length usually helps more than adding symbols, since it multiplies rather than nudges the total.
Frequently Asked Questions
How much entropy has a random 16-character password?
104.9 bits, using all 94 keyboard characters.
How much has a six-word passphrase?
77.5 bits, with words chosen at random from 7,776.