Password Strength Meter - Free Online Security Checker
Analyze password strength with entropy calculation, time-to-crack estimates, and detailed security feedback. Check how secure your passwords really are.
Check Password Strength
Your password is analyzed locally and never leaves your browser
Example Passwords
Strength Analysis
Enter a password to analyze its strength
Password Strength Levels
Very Weak (0-19)
Common passwords, very short, or single character type. Cracked instantly.
Weak (20-39)
Short passwords with limited character diversity. Cracked in seconds to minutes.
Medium (40-59)
Moderate length with some character diversity. May take hours to days to crack.
Strong (60-79)
Good length with character diversity. Could take years to crack.
Very Strong (80-100)
Long, random passwords with full character diversity. Virtually uncrackable.
🔐 Entropy Calculation
Calculate cryptographic entropy in bits to measure true password randomness and strength against brute force attacks.
⏱️ Time to Crack
Estimate how long it would take to brute force your password with modern computing power, from seconds to millennia.
📊 Detailed Analysis
Get comprehensive feedback on character diversity, patterns, and specific recommendations for improvement.
Free Online Password Strength Meter
Analyze password strength instantly with our free online tool. Calculate entropy, estimate time to crack, and get detailed security feedback. Perfect for checking existing passwords or testing new ones before use. All analysis happens locally in your browser for maximum privacy and security.
What Makes a Password Strong?
- Length: Longer passwords are exponentially harder to crack. Aim for at least 12 characters.
- Character Diversity: Use a mix of uppercase, lowercase, numbers, and symbols.
- Randomness: Avoid predictable patterns, sequences, or common words.
- Uniqueness: Don't reuse passwords across different accounts.
- Avoid Common Passwords: Stay away from passwords found in common password lists.
Understanding Password Entropy
Password entropy measures the unpredictability of a password in bits. Higher entropy means the password is more random and harder to guess. The formula for entropy is:
Where Character Set Size is the number of possible characters at each position. For example:
- Lowercase only: 26 possible characters
- Lowercase + Uppercase: 52 possible characters
- Lowercase + Uppercase + Numbers: 62 possible characters
- All characters: ~94 possible characters
Time to Crack Estimates
Our time-to-crack estimates are based on the following assumptions:
- Attack Speed: 1 billion guesses per second (modern GPU capability)
- Attack Method: Pure brute force (trying all possible combinations)
- No Optimization: No dictionary attacks, pattern recognition, or credential stuffing
- Single Target: Attacking one specific password
In reality, attackers often use more sophisticated methods that can crack passwords faster than pure brute force.
Common Password Weaknesses
- Short Length: Passwords under 8 characters are very weak
- Single Character Type: Using only letters or only numbers
- Predictable Patterns: Sequential numbers (123), keyboard patterns (qwerty), or repeating characters (aaa)
- Common Words: Using dictionary words, names, or common phrases
- Personal Information: Birthdays, anniversaries, pet names, or other easily discoverable information
- Password Reuse: Using the same password across multiple accounts
Tips for Creating Strong Passwords
- Use Passphrases: Combine multiple random words (e.g., "CorrectHorseBatteryStaple")
- Add Complexity: Mix character types and include symbols in unexpected places
- Make it Long: Aim for 16+ characters when possible
- Be Random: Use a password generator for truly random passwords
- Use a Password Manager: Let a password manager create and store strong, unique passwords for each account
- Enable 2FA: Use two-factor authentication whenever available for an extra layer of security
- Regular Updates: Change important passwords periodically, especially if you suspect they may have been compromised
Privacy & Security Guarantee
Your password security is our top priority. This tool operates entirely in your browser using JavaScript. Your passwords are never:
- Sent to any server or external service
- Stored in any database or log file
- Shared with third parties
- Used for any purpose other than the strength analysis you request
You can verify this by checking the network traffic in your browser's developer tools while using this tool.