What is Shannon entropy in passwords?

Entropy measures the unpredictability of a password in bits. A password with 60+ bits of entropy is generally considered secure against modern offline brute-force attacks.

What makes a truly strong password?

Length is the single most important factor. A 16+ character passphrase using diverse lowercase, uppercase, numbers, and symbols is exponentially harder to crack than a short complex string.

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Password Strength & Entropy

Calculate cryptographic entropy, character diversity, and estimated crack times under real-world brute-force models.

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Enter Password to Test

Entropy: 197.1 bitsRating: Very Strong

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Online Web Form

3.4007460000592177e+40 billion years

100 guesses/sec (rate limited)

GPU Workstation

3.400746000059218e+32 billion years

10 billion guesses/sec

Supercomputer Cluster

3.4007460000592173e+28 billion years

100 trillion guesses/sec

Character Variety

Length (>= 12 characters)

Lowercase letters (a-z)

Uppercase letters (A-Z)

Numbers (0-9)

Special symbols (!@#$)

Security Recommendations

Great password! It has strong entropy and meets modern security standards.

Understanding Real-World Password Cracking

Modern GPUs can test billions of hash combinations per second. Evaluating passwords using Shannon entropy rather than arbitrary scoring rules gives developers and security professionals realistic insight into vulnerability to offline attacks.