🔒 Password Strength Meter
Check how strong a password really is — entropy bits, estimated offline crack time, weakness flags. Type or paste any password for instant analysis.
About this tool
This tool measures password strength using Shannon entropy: the number of bits an attacker would need to guess the password by brute force, based on password length and the size of the character pool (lowercase 26, uppercase 26, digits 10, symbols 33). Higher entropy means harder to crack.
As you type, it estimates offline crack time at 10 billion guesses per second (a realistic rate for a GPU-based attack on stolen hashes), flags common passwords, sequential (abc, 123) and repeated (aaa) patterns, and shows a checklist of what to fix.
Example: Tr0ub4dor&3 scores about 56 bits (Weak — roughly 2 days to crack offline), while correct-horse-battery-staple reaches ~100 bits (Strong — billions of years). A 20-character truly random password with all character classes yields about 131 bits — essentially uncrackable.
FAQ
Why does my password score "Weak" even though it has symbols and numbers? ›
Entropy comes mainly from length × character-pool size. A short password with symbols (e.g. "P@ss1") has very few bits. A longer password using only lowercase letters can be stronger — length matters more than complexity.
What crack-time estimate should I trust? ›
The number shown assumes an offline attack against a fast hash (10¹⁰ guesses/sec), the worst case if a service is breached and passwords are weakly hashed. Online attacks against a login form are far slower (account lockout, rate limits), so the same password holds up longer there.
Is my password sent anywhere? ›
No. Everything runs in your browser — the password never leaves your device. You can disconnect from the internet and the tool still works.
Are the generated passwords safe to use for real accounts? ›
Yes. They are produced with the browser's cryptographic random generator (crypto.getRandomValues), the same source used for encryption keys. Always store them in a password manager.
How is this different from the Password Generator? ›
This tool focuses on analysing password strength — entropy, crack time, and weakness flags. The small built-in generator is for quick testing. For dedicated generation with passphrases, PINs, and bulk mode, use the Password Generator.