Password Strength Checker

The checker analyses your password using three methods running entirely in your browser: (1) It calculates the character pool size based on which character types are present (uppercase adds 26, lowercase 26, numbers 10, symbols 32). (2) It calculates entropy as length × log₂(pool size). (3) It scans for weakness patterns: repeated characters, sequential sequences, keyboard walks and common patterns. All analysis is JavaScript, local, with no network requests.

Entropy measures how many possible combinations a password could have. A password with N bits of entropy has 2ᴺ possible values. For a 16-character password with all character types (pool size 92), entropy = 16 × log₂(92) ≈ 105 bits, meaning 2¹⁰⁵ ≈ 40 billion trillion trillion possible combinations. That's astronomically large for any brute-force attack.

Yes. All analysis is JavaScript running in your browser, so the password never leaves your device. You can verify this yourself: open your browser's Network tab (DevTools → Network) while typing, and you'll see zero network requests are made. No data is sent, stored or logged.

That said, as a general security practice, be cautious about typing real passwords into any website you're not certain about. Our source code is completely transparent: plain HTML, CSS and JS with no obfuscation.

Aim for Strong (60+ bits) for everyday accounts and Very Strong (80+ bits) for high-value accounts such as email, banking, social media and cloud storage. A randomly generated 16-character password with all character types scores approximately 105 bits, well into Very Strong territory. Use our Password Generator to create one instantly.