Password Entropy Calculator

Calculate bits of entropy for your password. Understand password strength through information theory and cryptographic entropy.

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About Password Entropy

Learn how entropy measures password strength through cryptographic principles.

What Is Password Entropy?

Entropy measures password unpredictability in bits. One bit of entropy means 2 possible passwords, 2 bits means 4 possibilities, and so on. This exponential relationship means adding just a few characters dramatically increases entropy.

Entropy = log2(Possible Combinations). For security, aim for 80+ bits of entropy (approximately 16 random characters using all character types).

Entropy vs. Password Strength

While entropy is mathematical, password strength also depends on avoiding patterns and dictionary words. A 10-character password with true randomness beats a 12-character password with patterns.

Our calculator shows entropy, but remember: randomness from a generator beats manual creation every time.

Recommended Entropy Levels

For most accounts: 60+ bits. For sensitive accounts (email, banking): 80+ bits. For master passwords: 128+ bits. Use our entropy calculator to verify your passwords meet these standards. Generate high-entropy passwords with our password generator, and test how long they would take to crack with our time-to-crack estimator.

Bits Calculation

Calculate actual entropy in bits based on character set and length.

Combination Count

See the total number of possible passwords for your character set and length.

Strength Assessment

Get recommendations based on entropy level and use case.

Frequently Asked Questions

Questions about password entropy and calculation.

80+ bits of entropy is considered strong for most accounts. For critical accounts like email or banking, aim for 100+ bits. Master passwords should have 128+ bits.

Entropy is mathematical (based on character set and length). Strength also considers patterns and dictionary words. A truly random password with lower entropy beats a patterned password with higher theoretical entropy.

No, higher entropy is always better for security. The only downside is memorability if you're not using a password manager. For most accounts, use a manager and maximize entropy.

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