Password Strength Checker

security
authentication
tools
Evaluate the strength of passwords against modern security standards
Published

March 10, 2025

Password Strength Checker

This tool helps you evaluate the strength of passwords against modern security standards and common attack techniques.

Password Evaluation

Enter a password below to evaluate its strength. The password is evaluated locally in your browser and is never sent to our servers.

Understanding Password Strength

Password strength is determined by various factors:

Length

Password length is one of the most important factors. Longer passwords are generally more secure:

  • Less than 8 characters: Very weak
  • 8-11 characters: Weak
  • 12-15 characters: Medium
  • 16+ characters: Strong

Complexity

Password complexity refers to the mix of character types:

  • Lowercase letters: a-z
  • Uppercase letters: A-Z
  • Numbers: a-Z
  • Special characters: !@#$%^&*()_+-=|;:’“,.<>/?

Using all four character types greatly increases password strength.

Common Patterns

Attackers often check for common patterns:

  • Keyboard patterns: qwerty, 12345, asdfg
  • Repeated characters: aaabbb, 111222
  • Sequential characters: abcdef, 123456
  • Common substitutions: p@ssw0rd (instead of password)

Dictionary Words

Using common words makes passwords vulnerable to dictionary attacks. This includes:

  • Common words: password, welcome, baseball
  • Names: john, mary, smith
  • Dates: jan2023, 01012023
  • Pop culture references: starwars, superman

Entropy and Password Strength

Entropy is a measure of password unpredictability, typically measured in bits:

  • Less than 40 bits: Very weak
  • 40-60 bits: Weak
  • 60-80 bits: Medium
  • 80-100 bits: Strong
  • 100+ bits: Very strong

The entropy of a truly random password can be estimated as: log₂(C) × L, where C is the character set size and L is the password length.

Creating Strong Passwords

Passphrase Method

Create a memorable passphrase by combining random words:

  1. Choose 4-6 random words
  2. Combine them with spaces or special characters
  3. Add some capitalization and numbers

Example: Correct Horse Battery Staple or blue.ELEPHANT@swift42!MARBLE

Random Password Method

Use a password generator to create a truly random password:

  1. Generate a password with at least 16 characters
  2. Include all character types
  3. Use a password manager to store it securely

Example: p7X&tQ9Z$mR2vN4*

Password Manager Recommendations

We strongly recommend using a password manager to generate and store unique, complex passwords for each service you use. Popular options include:

  • Bitwarden
  • 1Password
  • KeePassXC
  • LastPass
  • Dashlane

Browser Password Strength Evaluation

This tool uses the following approaches to evaluate passwords:

  1. Character analysis: Checks length and character types
  2. Pattern detection: Looks for common patterns and sequences
  3. Dictionary checking: Compares against common password lists
  4. Entropy calculation: Estimates mathematical strength
  5. Breach checking: Checks if the password has appeared in known breaches

Security Considerations

When evaluating passwords:

  1. Never share your passwords: Even with this tool, your password is processed locally in your browser
  2. Use unique passwords: Each account should have a different password
  3. Change compromised passwords: If your password appears in a data breach, change it immediately
  4. Enable MFA/2FA: Add an extra layer of security with multi-factor authentication
  5. Regularly update critical passwords: Change passwords for sensitive accounts periodically

Additional Resources

For more information on password security: