Password Strength Checker
Analyze your password's strength with a detailed security report. Your password never leaves your browser — 100% private.
Estimated Time to Crack
Password Security Tips
About the Password Strength Checker
This password strength checker analyzes your password's security using multiple factors: length, character diversity, entropy, and pattern detection. It estimates how long it would take different types of attacks to crack your password, from a slow online attack (1,000 guesses/second) to a fast offline GPU attack against MD5 hashes (billions of guesses/second).
All analysis happens 100% in your browser. Your password is never sent to any server, logged, or stored. We use JavaScript to calculate entropy and run heuristic checks — no data leaves your device.
What Makes a Password Strong?
Password strength is primarily determined by entropy — the measure of unpredictability. Entropy is calculated as: Entropy = length × log₂(charset_size). A password with 70+ bits of entropy is considered very strong against modern attacks.
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📏LengthThe single most important factor. Each additional character multiplies the search space. A 16-character password is astronomically stronger than an 8-character one.
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🔤Character DiversityUsing all four character types (lowercase, uppercase, digits, symbols) increases the charset size from 26 to 95 possible characters per position.
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🎲RandomnessRandom passwords are stronger than memorable ones. "P@ssw0rd" is weak despite having symbols — it follows a predictable substitution pattern.
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🚫No PatternsSequential characters (abc, 123), keyboard walks (qwerty), and repeated characters (aaa) dramatically reduce entropy.
Frequently Asked Questions
Is it safe to type my password here?
Yes — this password strength checker is 100% client-side. Your password is analyzed entirely in JavaScript running in your browser and is never transmitted to any server. You can also disconnect from the internet and use this tool with the same result. We do not store, log, or have any access to passwords entered here.
What is password entropy?
Password entropy measures unpredictability in bits. It is calculated as length × log₂(charset size). If you use only lowercase letters (26 chars), an 8-character password has 8 × log₂(26) ≈ 37.6 bits of entropy. Adding uppercase, numbers, and symbols (95 chars) gives 8 × log₂(95) ≈ 52.4 bits. Security experts recommend at least 60–70 bits for important accounts.
How long would it take to crack my password?
Crack time depends on attack type and password strength. An online brute-force attack (throttled at ~1,000/sec) would take centuries for even a moderate password. An offline attack against an MD5 hash can test billions per second with GPUs. A bcrypt hash with a work factor of 12 is ~500,000× slower than MD5, making even somewhat weak passwords much harder to crack offline.
What is the difference between a weak and strong password?
"Password123" scores as weak because it uses common dictionary words and predictable patterns. "x9!kPq#2mZr$" scores as strong because it has length, mixed character types, and no patterns. But "correct-horse-battery-staple" (a passphrase) also scores well — its length compensates for using only lowercase letters.
Should I use a password manager?
Yes. Password managers (like Bitwarden, 1Password, or Dashlane) generate and store long, random, unique passwords for every site. Since you don't need to memorize them, they can be 20+ characters of true randomness — far stronger than any human-memorable password. You only need to remember one strong master password.
How often should I change my passwords?
Modern security guidance (NIST 800-63B) recommends you do NOT change passwords regularly unless there is evidence of compromise. Frequent mandatory changes lead users to choose weaker passwords (incrementing a number) and reduce overall security. Instead: use strong unique passwords for each account, enable 2FA, and change immediately if a breach occurs.