Password entropy, in bits.

How it works

• Characters: entropy = length × log₂(pool size). A 16-character password from 62 letters and digits carries about 95 bits.
• Diceware words: entropy = words × log₂(list size). The EFF long list holds 7,776 words (6⁵, five dice), so each word adds about 12.9 bits and six words give 77 bits; its short list (1,296 words) gives 10.3 bits per word (EFF).
• Guesses: every extra bit doubles the guesses needed. On average an attacker finds the secret after half the search space, 2^bits−1 guesses. The time shown uses the guess rate you enter; it is arithmetic, not a prediction.
• Only for random secrets: the formulas assume every character or word was chosen uniformly at random. NIST SP 800-63B notes that estimating entropy for user-chosen passwords is challenging, so a password you made up cannot be scored this way. For that, use the Password Strength Checker; to get a random one, use the Diceware generator.