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Password Entropy Calculator
Measure password strength in bits of entropy and estimate crack times.
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About this tool
Understand exactly how strong your password really is. Paste or type a password (masked by default, with a show/hide toggle) and the calculator measures its entropy in bits based on the character set used — lowercase, uppercase, digits, symbols. It then estimates crack time across three threat models: online throttled attack (100 guesses/second), offline fast attack (10 billion/second), and GPU cluster (100 trillion/second). A visual strength meter and actionable suggestions help you improve weak passwords. An inline explainer answers 'Why is length more important than complexity?'
How to use
- 1 Type or paste your password in the input field.
- 2 Use the eye icon to toggle visibility.
- 3 Read your entropy in bits and the strength rating.
- 4 Check the crack-time table for different attack scenarios.
- 5 Follow the improvement suggestions to make your password stronger.
Frequently Asked Questions
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