Password Strength Checker
Check the strength of your passwords in real-time. Analyze entropy, detect common patterns, get security recommendations, and estimate time to crack. All analysis happens locally in your browser — your password never leaves your device.
100% Client-Side Analysis
Your password is analyzed entirely in your browser. No data is sent to any server. Your password never leaves your device.
What is Password Strength?
**Password strength** measures how resistant a password is to being guessed or cracked by attackers. A strong password is difficult to guess through brute-force attacks, dictionary attacks, or pattern recognition.
Password strength depends on several factors:
- Length — Longer passwords are exponentially harder to crack. Each additional character significantly increases the number of possible combinations.
- Character Variety — Mixing uppercase, lowercase, numbers, and symbols increases the possible character combinations.
- Randomness — Avoiding predictable patterns, dictionary words, sequences, and personal information makes passwords harder to guess.
- Uniqueness — Using different passwords for each account prevents one breach from compromising multiple accounts.
Our Password Strength Checker analyzes these factors and provides a comprehensive strength assessment, security recommendations, and time-to-crack estimates.
How Password Strength is Calculated
Our strength checker evaluates passwords based on multiple criteria:
1. Length Analysis
Password length is the most important factor in security. Longer passwords are exponentially harder to crack:
- 8-11 characters — Minimum acceptable length
- 12-15 characters — Good security
- 16+ characters — Excellent security
- 20+ characters — Maximum security
2. Character Variety
Using multiple character types increases the possible combinations:
- Uppercase letters (A-Z) — Adds 26 possible characters
- Lowercase letters (a-z) — Adds 26 possible characters
- Numbers (0-9) — Adds 10 possible characters
- Symbols (!@#$%^&*) — Adds 33+ possible characters
A password using all character types has 95 possible characters per position, making it much harder to crack than a password using only lowercase letters (26 possible characters).
3. Entropy Calculation
**Entropy** measures the randomness and unpredictability of a password in bits. Higher entropy means more possible combinations:
- < 28 bits — Very weak (can be cracked instantly)
- 28-40 bits — Weak (can be cracked in hours to days)
- 40-50 bits — Fair (can be cracked in months to years)
- 50-60 bits — Good (would take centuries to crack)
- 60-70 bits — Strong (would take millions of years)
- 70+ bits — Very strong (would take billions of years)
Entropy is calculated as: length × log₂(character set size)
4. Pattern Detection
The checker identifies common patterns that weaken passwords:
- Keyboard patterns — qwerty, asdfgh, 123456
- Sequences — abc123, 12345, 98765
- Repeated characters — aaa, 111, ###
- Dictionary words — Common passwords like "password", "admin"
- Common substitutions — p@ssw0rd, l33t speak patterns
Password Strength Levels
Very Weak (0-29)
Passwords that can be cracked almost instantly. Typically too short, use only one character type, or are very common passwords.
Examples: "password", "123456", "abc", "qwerty"
Weak (30-49)
Passwords that can be cracked in hours to days. May be too short, lack character variety, or contain common patterns.
Examples: "password123", "MyPassword", "abc12345"
Fair (50-64)
Passwords with basic security. May be adequate for low-risk accounts but should be improved for important accounts.
Examples: "MyPass123", "SecureP@ss", "Hello2023!"
Good (65-79)
Passwords with good security. Suitable for most accounts. Contains good length and character variety.
Examples: "MySecureP@ss123", "Tr0ub@dor&3", "P@ssw0rd2023!"
Strong (80-89)
Passwords with strong security. Excellent for important accounts. Long length, full character variety, no patterns.
Examples: "MyV3ryS3cur3P@ssw0rd!", "R@nd0mP@ss2023#", "S3cur3Ch@r12!"
Very Strong (90-100)
Passwords with maximum security. Ideal for critical accounts. Very long, highly random, full character variety.
Examples: "X7#mK9$pL2@vN4!wQ5%rT6&yU8*", "aB3$cD5#eF7@gH9!jK1@mL3#nO5$pQ7%"
Password Security Best Practices
1. Use Long Passwords
Length is the most important factor. Aim for at least 12-16 characters for most accounts, and 20+ characters for critical accounts (email, banking, etc.).
Each additional character exponentially increases the number of possible combinations, making brute-force attacks impractical.
2. Use Full Character Variety
Include uppercase letters, lowercase letters, numbers, and symbols in your passwords. This maximizes the character set size and increases entropy.
A password using all character types has 95 possible characters per position, compared to only 26 for lowercase-only passwords.
3. Avoid Common Patterns
Don't use:
- Dictionary words or common phrases
- Keyboard patterns (qwerty, asdfgh, 123456)
- Sequences (abc123, 12345, 98765)
- Repeated characters (aaa, 111, ###)
- Personal information (names, birthdays, addresses)
- Common passwords (password, admin, welcome)
4. Use Unique Passwords
Never reuse passwords across multiple accounts. If one account is compromised, all accounts using the same password become vulnerable.
Use a password manager to generate and store unique, strong passwords for each account.
5. Enable Two-Factor Authentication
Even with a strong password, enable two-factor authentication (2FA) whenever possible. This adds an extra layer of security by requiring a second verification method (SMS, authenticator app, hardware key).
2FA significantly reduces the risk even if your password is compromised.
6. Use a Password Manager
Password managers help you:
- Generate strong, random passwords
- Store unique passwords for each account
- Auto-fill passwords securely
- Keep passwords encrypted and secure
Popular password managers include Bitwarden, 1Password, LastPass, and Dashlane.
7. Change Passwords After Breaches
If a service you use experiences a data breach, change your password immediately. Use services like Have I Been Pwned to check if your email has been involved in known data breaches.
Common Password Mistakes
Using Personal Information
Don't use names, birthdays, addresses, pet names, or other personal information that attackers might know or find through social media.
Using Dictionary Words
Dictionary words are vulnerable to dictionary attacks. Even with character substitutions (p@ssw0rd), they're easily cracked.
Using Patterns
Avoid keyboard patterns (qwerty), sequences (12345), or repeated characters (aaa). These are predictable and easily guessed.
Password Reuse
Using the same password across multiple accounts means one breach compromises all your accounts. Always use unique passwords.
Writing Down Passwords
Writing passwords on paper or in unencrypted files is a security risk. Use a password manager instead.
Sharing Passwords
Never share passwords with others, even family or coworkers. Each person should have their own account with their own password.
Frequently Asked Questions
Yes. All password analysis happens entirely in your browser — your password never leaves your device. No data is sent to any server, stored, or logged. This tool is completely safe to use with any password, including your real passwords.
Entropy measures the randomness and unpredictability of a password in bits. Higher entropy means more possible combinations, making the password harder to crack. It's calculated as: length × log₂(character set size). For example, a 12-character password using uppercase, lowercase, numbers, and symbols (95 possible characters) has approximately 79 bits of entropy.
For most accounts, use at least 12-16 characters. For critical accounts (email, banking, etc.), use 20+ characters. Length is the most important factor in password security — longer passwords are exponentially harder to crack. Each additional character significantly increases the number of possible combinations.
A strong password is long (12+ characters), uses full character variety (uppercase, lowercase, numbers, symbols), avoids common patterns (keyboard patterns, sequences, dictionary words), and is unique to each account. Randomness is also important — unpredictable passwords are much harder to crack than predictable ones.
Time to crack estimates are rough approximations based on entropy and assume a typical brute-force attack with modern computing power. Actual cracking times depend on many factors including the attacker's resources, attack method (brute-force, dictionary, rainbow tables), and whether the password hash is available. These estimates are for comparison purposes only.
Yes. Password managers help you generate strong, unique passwords for each account, store them securely, and auto-fill them when needed. They're essential for managing many accounts securely. Popular options include Bitwarden (free and open-source), 1Password, LastPass, and Dashlane.
No. Never reuse passwords across multiple accounts. If one account is compromised (through a data breach, phishing, or other attack), all accounts using the same password become vulnerable. Always use unique passwords for each account.
Two-factor authentication adds an extra layer of security by requiring a second verification method in addition to your password. This could be a code sent via SMS, an authenticator app (like Google Authenticator or Authy), or a hardware security key. Even if your password is compromised, 2FA prevents unauthorized access. Enable 2FA whenever possible, especially for important accounts.
Avoid keyboard patterns (qwerty, asdfgh, 123456), sequences (abc123, 12345, 98765), repeated characters (aaa, 111, ###), dictionary words (even with substitutions like p@ssw0rd), personal information (names, birthdays), and common passwords (password, admin, welcome). These patterns make passwords predictable and easy to crack.
Modern security recommendations suggest changing passwords only when necessary (after a data breach, if you suspect it's compromised, or if the service requires it). With strong, unique passwords and 2FA enabled, frequent password changes are usually unnecessary and can lead to weaker passwords. However, always change passwords immediately after a known breach.