Password Entropy Calculator
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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Measure Your Password Security
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.
Why Measure Password Entropy?
Quantify Security Objectively
Entropy gives a mathematical measure of password strength, not just subjective ratings.
Understand Attack Resistance
Higher entropy means exponentially more guesses needed for brute-force attacks.
Compare Password Strategies
See how length vs. complexity affects security using measurable bits.
Meet Security Standards
Many security policies specify minimum entropy requirements (e.g., 80+ bits).
How to Use This Calculator
Frequently Asked Questions
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.