Password Strength.
Check how strong your password is with entropy analysis and crack time estimates.
About Password Strength Checker
A strong password is your first line of defense. This tool analyzes passwords by calculating Shannon entropy (a measure of randomness), estimating how long a brute-force attack would take under four different scenarios (online throttled, online unthrottled, offline slow hash, offline fast hash), and providing actionable suggestions to improve strength. Use it to evaluate password policies, test generated passwords, or educate users about what makes a password secure.
How to Use
- Enter the password you want to analyze.
- Click "Check Strength" to see the full analysis.
- Review entropy, crack time estimates, and improvement suggestions.
Key Features
- ✓ Shannon entropy calculation in bits
- ✓ Crack time estimation for 4 attack scenarios
- ✓ Character set detection (lowercase, uppercase, digits, symbols)
- ✓ Actionable improvement suggestions
- ✓ Visual strength meter with score
Common Use Cases
- • Evaluating password strength before use
- • Testing password policies and generators
- • Educating users about password security
- • Comparing different password strategies
Frequently Asked Questions
What is password entropy?
Entropy measures the randomness of a password in bits. It is calculated as length × log2(pool size), where pool size is the number of possible characters. Higher entropy means more combinations to try.
How are crack times estimated?
Crack times assume brute-force attacks at different speeds: 10/sec (online throttled), 100/sec (online unthrottled), 10,000/sec (offline with bcrypt), and 10 billion/sec (offline with MD5). Real times depend on the hashing algorithm used.
Is my password sent to a server?
The password is sent via POST for analysis but is never stored. For maximum privacy, use this tool in the dashboard (requires login) where HTTPS encrypts the transmission.
What makes a strong password?
A strong password is long (12+ characters), uses multiple character sets (uppercase, lowercase, digits, symbols), and avoids common patterns, dictionary words, and sequential characters.