Password Strength Checker
Analyze password security with entropy calculation and crack time estimation.
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Assuming 10 billion guesses/second- Enter a password to see suggestions
| Length | 0 |
|---|---|
| Entropy | 0 bits |
| Character Set Size | 0 |
| Unique Characters | 0 |
What Is Password Strength?
Password strength measures how resistant a password is to being guessed or cracked by an attacker. It depends on length, character diversity, unpredictability, and whether the password appears in known data breach databases. A strong password is the first line of defense for any online account, server, or encrypted resource.
How Is Password Strength Measured?
Password strength is evaluated based on several factors:
- Length: Longer passwords exponentially increase the number of possible combinations. Each additional character multiplies the search space.
- Character Variety: Using uppercase, lowercase, numbers, and symbols dramatically increases entropy.
- Entropy (bits): A mathematical measure of randomness. A password with 80+ bits of entropy is considered strong for most purposes.
- Dictionary Check: Common words, names, and keyboard patterns (e.g., "qwerty", "password123") are flagged as weak regardless of length.
- Breach Database Check: Passwords found in known data breaches (e.g., Have I Been Pwned) are marked as compromised.
Password Strength Levels
| Strength | Characteristics | Crack Time (Estimate) |
|---|---|---|
| Very Weak | Short, common words, no variety | Seconds to minutes |
| Weak | Short with some variety, or common patterns | Hours to days |
| Fair | Medium length, mixed characters | Weeks to months |
| Strong | 12+ characters, high variety, no patterns | Years to centuries |
| Very Strong | 16+ characters, fully random, all character types | Millions of years+ |
Tips for Strong Passwords
- Use a password manager: Generate and store unique random passwords for every account.
- Use passphrases: Four or more random words (e.g., "correct horse battery staple") are both strong and memorable.
- Minimum 12 characters: Modern hardware can crack shorter passwords relatively quickly.
- Enable two-factor authentication (2FA): Even a strong password should be backed by a second factor.
- Never reuse passwords: A breach on one site should not compromise all your accounts.
How to Use This Tool
- Type or paste a password into the input field.
- View the real-time strength analysis and score.
- Review specific feedback on what makes the password strong or weak.
- Follow the suggestions to improve your password strength.
Why Use This Tool?
- Get instant, detailed feedback on password security.
- Checks for common patterns, dictionary words, and character variety.
- Visual strength meter makes it easy to understand the rating.
- All analysis runs locally — your password is never sent anywhere.
Frequently Asked Questions
Is a longer password always better?
Generally yes, but only if it is not a predictable pattern. "aaaaaaaaaaaaaaaa" is long but trivially crackable. Length combined with randomness is what matters.
Are special characters required?
Not strictly. A 20-character passphrase of random words is stronger than an 8-character password with special characters. However, using all character types in shorter passwords significantly increases strength.