Free Password Strength Checker
Instantly analyse any password with a visual strength meter, entropy score, estimated crack time and personalised improvement tips.
About the Password Strength Checker
This tool analyses your password locally in the browser — nothing you type is ever transmitted to a server. The strength analysis is based on multiple factors: length, character set diversity, entropy (bits of randomness), and common pattern detection.
The estimated crack time assumes an offline brute-force attack at 10 billion guesses per second, which reflects modern GPU-accelerated cracking hardware. For common hash algorithms (MD5, SHA-1) real attacks can be even faster — which is why high entropy matters so much.
The improvement tips give you actionable steps to bring any weak password up to a strong standard quickly.
How to Use the Password Strength Checker
Type or Paste Password
Enter any password into the input field. Analysis updates in real time as you type.
Read the Strength Meter
The colour-coded bar shows strength from Very Weak (red) to Very Strong (green).
Review Entropy & Crack Time
Check how many bits of entropy your password has and how long it would take to brute-force.
Apply Improvement Tips
Follow the personalised tips to strengthen your password until the meter turns green.
Key Features
- Real-time analysis as you type — no button press needed
- 5-level strength scale: Very Weak → Very Strong
- Entropy calculation in bits based on effective charset size
- Estimated crack time at 10B guesses/second
- Character type breakdown (lowercase, uppercase, numbers, symbols)
- Personalised improvement tips for each weakness detected
- Toggle password visibility without clearing the field
- Zero server communication — 100% private
Frequently Asked Questions
No. The entire analysis runs in your browser using JavaScript. Your password is never transmitted over the network — not even anonymised telemetry is collected.
Entropy measures password unpredictability in bits. It is calculated as length × log₂(charset_size). A 50-bit password requires up to 2⁵⁰ guesses to crack. Aim for 80+ bits for strong protection.
Short length, using only one character type (e.g. only lowercase), using dictionary words or common patterns like "123456" or "password", and reusing passwords across sites all significantly weaken a password.
Crack time is estimated based on entropy, assuming 10 billion guesses per second — representative of an offline attack with modern GPU hardware cracking an unsalted MD5 hash. Salted bcrypt/Argon2 hashes would take orders of magnitude longer.