How much entropy is enough?

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.

Is a longer password always better?

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.

How are crack times calculated?

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.

Does this calculator store my password?

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.

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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.