Password Strength Checker

This tool checks six criteria: length (8+ and 12+), presence of uppercase letters, lowercase letters, numbers, and special characters. Each criterion adds to the overall score, which maps to Very Weak / Weak / Fair / Good / Strong / Very Strong. It also estimates entropy — the mathematical unpredictability in bits.

Entropy measures how hard a password is to brute-force. It's calculated from the character set size and length: entropy = length × log₂(charset size). A 16-character password using all character types has roughly 95–104 bits of entropy — considered very strong against modern attacks.

No. Everything runs entirely in your browser. Your password never leaves your device and is never sent to any server. You can disconnect from the internet and the tool will still work.

Length is the most important factor — each additional character multiplies the search space exponentially. Combine length (12+ characters) with character variety (uppercase, lowercase, numbers, symbols) and avoid dictionary words, names, or common patterns. A passphrase (four random words) can be both strong and memorable.

A strength checker evaluates a password you already have — or one you're considering — and tells you how secure it is. A password generator creates new random passwords for you. For best security, use the DevPlaybook Password Generator to create a strong password, then check it here to confirm it meets your standards.