How to Use the Password Strength Checker & Entropy
1
Enter Password
Type or paste a password into the test field.
2
Check Strength Rating
Review the strength assessment (Weak, Moderate, Strong, Extremely Strong).
3
Inspect Entropy & Crack Time
View the estimated bits of entropy and brute-force crack time.
4
Review Checklist
Ensure all security recommendations (length, numbers, symbols) are green.
Password Information Entropy Formula
Entropy measures the unpredictability of a password in bits:
Entropy (E) = Length × log₂(Charset Size)
Where Charset Size is 26 for lowercase, 52 for mixed case, 62 for letters+digits, and 94 for all ASCII characters. Passwords above 60 bits are considered strong.
Why Choose Our Password Strength Checker & Entropy?
Calculates information entropy (bits)
Estimates brute-force crack times at 100 billion guesses/sec
Security checklist for character sets and length
Color-coded visual strength badge
100% private in-browser testing — no passwords stored or sent
Pro Tips for Best Results
- Passphrases composed of 4-5 random words (e.g. "correct-horse-battery-staple") offer high entropy while remaining easy to remember.
- Never reuse the same password across multiple online accounts; use a password manager.