Password Entropy Checker
Developer utilities: formatters, validators, encoders, and testers.
What does this tool do?
Find out how strong your password really is. This tool calculates entropy in bits from the character sets you use, shows a visual strength meter, and estimates how long it would take to crack - with zero data leaving your browser.
Key features
- Syntax validation
- Format & minify
- Error highlighting
- Copy formatted output
Find out how strong your password really is. This tool calculates entropy in bits from the character sets you use, shows a visual strength meter, and estimates how long it would take to crack - with zero data leaving your browser.
Password Input
Strength
Crack-Time Estimates
Estimates assume brute force over the full character set. Real attacks using dictionaries and patterns are faster - length beats complexity.
How to Use
- Type any password into the input box (use Show password to see it).
- Read the entropy in bits, the strength label and the animated meter.
- Check the crack-time estimates for online vs offline attacks.
Core Features
- True entropy math: length x log2(character set size)
- Crack-time estimates at two realistic attack speeds
- Visual strength meter with Weak-to-Very-strong labels
- Zero storage, zero network - analysis is 100% local
Frequently Asked Questions
How many bits of entropy do I need?
Aim for 80+ bits for important accounts - that is roughly a 13-character random mix of letters, digits and symbols, or 6-7 random words. Below 40 bits can fall in seconds to offline attacks.
Is a long passphrase better than a complex short password?
Usually yes. Each extra character multiplies cracking time by the character-set size, so "correct horse battery staple" style passphrases beat short complex ones like "P@ssw0rd!" - which attackers also guess first.
How to Use Password Entropy Checker
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