Password Strength Checker — Entropy & Crack Time Estimator
Analyze password security. Calculate entropy. Estimate crack time.
💡 Password Best Practices
- Use 12+ characters (16+ is better)
- Mix uppercase, lowercase, numbers, and symbols
- Avoid dictionary words, names, and dates
- Use unique passwords for each account
- Consider using a password manager
- Enable two-factor authentication (2FA)
About Password Strength Checker
Analyze password strength with real-time entropy calculation, crack time estimation, and security recommendations. Checks for length, character variety, common patterns, and provides actionable feedback to improve security.
Perfect for creating new passwords, auditing existing ones, or understanding password security. All analysis happens locally in your browser - your passwords are never transmitted or stored.
How to Use Password Strength Checker
- Type or paste a password to analyze.
- View strength rating (Weak/Fair/Good/Strong).
- Check entropy bits and crack time estimate.
- Review security recommendations.
- Improve password based on feedback.
Key Features
Real-time strength analysis
Entropy calculation (bits)
Crack time estimation
Pattern detection
Dictionary word checking
Character variety analysis
Length validation
Security recommendations
Visual strength meter
100% client-side
Frequently Asked Questions
What is password entropy?
Entropy measures password unpredictability in bits. Higher entropy means more possible combinations, making the password harder to crack. A strong password should have 60+ bits of entropy.
How is crack time estimated?
Crack time is calculated based on password entropy and assumed attack speed (1 billion guesses/second for online, 100 billion for offline). Real attack speeds vary by hardware and method.
Is my password safe to enter here?
Yes! All calculations happen 100% in your browser using JavaScript. No passwords are sent to any server, stored, or logged anywhere. Completely private.
What makes a strong password?
Strong passwords are: 12+ characters long, mix uppercase/lowercase/numbers/symbols, avoid dictionary words, don't use personal info, and are unique per account.
Should I use a password manager?
Yes! Password managers generate and store strong, unique passwords for each account. They're the best way to maintain strong passwords without memorizing dozens of complex strings.