Calculate the entropy (strength in bits) of a password based on character set and length. Evaluate password security against brute-force attacks.
Entropy measures the unpredictability of a password. Higher entropy means it is mathematically harder for a computer to guess.
Length usually wins. A longer phrase (e.g., 'CorrectHorseBatteryStaple') often has higher entropy than a short complex password like 'Tr0ub4dor&3'.
Aim for > 60 bits.