Measure password security by calculating entropy in bits. Analyze character sets, estimate crack times, and get recommendations for stronger passwords based on information theory.
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Password entropy measures the unpredictability of a password using information theory. Higher entropy means more possible combinations and greater resistance to brute-force attacks. Our calculator analyzes your password's character composition and provides accurate security metrics.
Entropy gives a mathematical measure of password strength, not just subjective ratings.
Higher entropy means exponentially more guesses needed for brute-force attacks.
See how length vs. complexity affects security using measurable bits.
Many security policies specify minimum entropy requirements (e.g., 80+ bits).
Password entropy is a measure of password strength expressed in bits. It represents the number of binary decisions (coin flips) needed to guess the password. Each additional bit doubles the number of possible combinations.
For online accounts: 40-60 bits is reasonable with rate limiting. For offline security (encrypted files): 80+ bits recommended. For critical cryptographic keys: 128+ bits is the standard.
Yes, length is the primary factor. A 16-character lowercase password has more entropy (~75 bits) than an 8-character password with all character types (~52 bits). Length beats complexity.
Crack times assume brute-force attacks at various speeds: online attacks (throttled to ~1000/sec), offline attacks on fast hashes (~10 billion/sec), or GPU clusters (~100 billion/sec). Average time is half the maximum search space.
No. All calculations happen in your browser. Your password is never sent to any server or stored anywhere. You can verify this in your browser's network tab.