Password Strength Checker
Free online password strength checker, estimate crack time
About Password Strength Checker
Evaluates password strength in real time using a heuristic scoring algorithm that combines length, character variety, common-pattern penalties, and entropy, then estimates brute-force crack time at 10 billion guesses per second. It also includes a built-in generator (length 4-64, uppercase/lowercase/numbers/symbols) and reports six criteria checks (>=8 chars, uppercase, lowercase, digit, symbol, >=12 chars) with pass/fail indicators.
How to Use
1. Type or paste a password into the input (use the eye icon to toggle visibility, the X to clear, the copy icon to copy). 2. Or use the generator: set length (4-64) via the slider, tick the character sets, and click Generate. 3. The Strength Meter card updates live with a 0-100 score, color bar, and label (very weak / weak / fair / strong / very strong). 4. The three stat cards show estimated crack time, password length, and entropy in bits. 5. The Criteria card lists which checks passed (green check) or failed (gray X).
Scoring & Crack-Time Model
Score starts at 0 and adds min(30, length*2) for length, +10 per character variety (upper/lower/digit/symbol), +10 if length >= 12, +10 if length >= 16, with penalties for 3+ repeated characters (-10) and common prefixes like password/qwerty/abc/123/admin (-20). Entropy = length * log2(poolSize) where pool sizes are 26/26/10/32. Crack time assumes 1e10 guesses/second: combinations = poolSize^length / guessesPerSecond. Thresholds map to very weak (<20), weak (20-39), fair (40-59), strong (60-79), very strong (80+).
▶How realistic is the estimated crack time?
▶Why does a long password still score poorly?
▶Is my password sent anywhere when I check it?
▶What character pool sizes are used for entropy?
If this tool has been helpful to you, consider buying me a coffee.
Buy me a coffee