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Entropy Calculator

Estimate password entropy in bits and see how length and character set size affect guessing resistance.

Local processing

Entropy Calculator

What is Entropy Calculator?

Entropy Calculator estimates how much unpredictability a password contains. Entropy is measured in bits; each additional bit doubles the number of guesses an attacker needs.

How It Works

The character set size is detected from the characters used (lowercase, uppercase, digits, symbols and spaces). Entropy equals length multiplied by log2 of the character set size, with a rough strength label attached.

Common Use Cases

  • Comparing password policies
  • Explaining why length matters
  • Reviewing generated passwords
  • Security awareness training

Technical Details

Uses the standard entropy formula length × log2(charsetSize). It is an estimate that assumes random character selection and does not model dictionary attacks.

How to Use

Enter your input above. The result updates automatically. Use the copy button to copy the result.

Privacy

All processing happens in your browser. Your data is never uploaded to any server.

FAQ

Does high entropy guarantee a safe password?

No. Entropy measures unpredictability under a random-character model. Passwords made of common words can still be weak despite a high estimate.

Is my data uploaded to a server?

No. Everything runs locally in your browser. Your input never leaves your device.

Does Entropy Calculator work on mobile?

Yes. The interface is responsive and works in modern mobile browsers without installing an app.

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