Password Strength Tester

Q: What makes a password strong?

A strong password has at least 12-16 characters, combines uppercase and lowercase letters, numbers, and special symbols, avoids dictionary words and common patterns, doesn't contain personal information, and is unique for each account. Password entropy of 60+ bits is considered strong.

Q: How is password entropy calculated?

Password entropy is calculated using the formula: Entropy = L × log₂(R), where L is the password length and R is the character pool size (number of possible characters). Higher entropy means more possible combinations, making the password harder to crack.

Q: How long would it take to crack my password?

Crack time depends on password entropy and attack method. Online attacks (limited attempts) take longer than offline attacks on stolen databases. A 12-character password with mixed characters might take centuries to crack via brute force, while a simple 6-character password could be cracked in seconds.

Q: Is my password checked against a leaked password database?

This tool performs all analysis locally in your browser. Your password is never sent to any server or checked against external databases. For additional security, you can use services like HaveIBeenPwned to check if your password appears in known data breaches.

Q: Should I use a password manager?

Yes, password managers are highly recommended. They generate and store unique, complex passwords for each account, so you only need to remember one master password. This eliminates password reuse, which is one of the biggest security risks.

Analyze password strength with real-time security scoring, entropy calculation, time-to-crack estimation, and detailed improvement suggestions. Test your password security instantly.

Free to useNo sign-up requiredUpdated Jan 2026

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Enter a password to analyze its strength

Your password is analyzed locally and never leaves your browser

Secure Password Generator

Lowercase (a-z)

Uppercase (A-Z)

Numbers (0-9)

Symbols (!@#$)

Length: 16

Click "Generate" to create a password

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About Password Strength Tester

Welcome to the Password Strength Tester, an advanced security analysis tool that evaluates your password's strength in real-time. Get a comprehensive security score, entropy calculation, time-to-crack estimation across multiple attack scenarios, and personalized improvement suggestions. All analysis happens locally in your browser - your password is never sent to any server.

What Makes a Strong Password?

A strong password is your first line of defense against unauthorized access. Here are the key characteristics:

Length: At least 12-16 characters. Longer passwords exponentially increase security.
Complexity: Mix of uppercase, lowercase, numbers, and special symbols.
Uniqueness: Avoid common words, phrases, and previously breached passwords.
Randomness: No predictable patterns like "123456" or "qwerty".
Exclusivity: Use a unique password for each account.

How to Use This Tool

Enter your password: Type or paste your password in the input field. Analysis starts immediately.
Review the security score: Check your score (0-100) and strength level. Aim for 80+ for important accounts.
Analyze the breakdown: Review character composition, entropy, and crack time estimates.
Follow suggestions: Address any improvement suggestions to strengthen your password.
Generate secure passwords: Use the built-in generator to create cryptographically secure passwords.

Understanding Your Security Score

Score Range	Strength Level	Recommendation
0-19	Weak	Highly vulnerable. Change immediately.
20-39	Fair	Insufficient for most accounts. Improve length and complexity.
40-59	Good	Acceptable for low-risk accounts. Add more variety.
60-79	Strong	Good for most purposes. Consider adding symbols.
80-100	Excellent	Highly secure. Suitable for sensitive accounts.

Password Entropy Explained

Entropy measures the randomness and unpredictability of a password, expressed in bits. Higher entropy means more possible combinations, making the password harder to crack.

Entropy Formula

Entropy = L × log₂(R)

Where:

L = Password length (number of characters)
R = Character pool size (possible characters)

Character Pool Sizes

Character Type	Pool Size	Example
Lowercase letters only	26	abcdefgh
+ Uppercase letters	52	AbCdEfGh
+ Numbers	62	AbC123Gh
+ Symbols	94+	AbC!23@Gh

Entropy Guidelines

Entropy (bits)	Security Level	Use Case
< 28	Very Weak	Not recommended for any use
28-35	Weak	Low-value accounts only
36-59	Reasonable	Standard online accounts
60-127	Strong	Email, banking, sensitive data
128+	Very Strong	Cryptographic keys, master passwords

Time-to-Crack Estimation

This tool estimates how long it would take to crack your password under three different attack scenarios:

Attack Scenarios

Online Throttled (100/sec): Rate-limited attacks against live services with lockout protection.
Fast Hash (10B/sec): Offline attack on stolen database with weak hashing (MD5, SHA1).
Slow Hash (10K/sec): Offline attack against properly secured databases using bcrypt or Argon2.

Common Password Mistakes

Dictionary words: "password", "monkey", "dragon" are among the most common.
Sequential patterns: "123456", "abcdef", "qwerty" are easily guessed.
Personal information: Names, birthdays, and pet names are vulnerable to social engineering.
Simple substitutions: "p@ssw0rd" is almost as weak as "password".
Repeated characters: "aaaaaa" or "111111" provide minimal security.
Password reuse: Using the same password across multiple accounts.

Password Security Best Practices

Use a password manager: Generate and store unique passwords for every account.
Enable 2FA/MFA: Add an extra layer of security beyond just passwords.
Use passphrases: Consider using 4-5 random words like "correct-horse-battery-staple".
Change compromised passwords: If a service is breached, change your password immediately.
Check for breaches: Use Have I Been Pwned to check if your accounts have been compromised.

Frequently Asked Questions

What makes a password strong?

A strong password has at least 12-16 characters, combines uppercase and lowercase letters, numbers, and special symbols, avoids dictionary words and common patterns, does not contain personal information, and is unique for each account. Password entropy of 60+ bits is considered strong.

How is password entropy calculated?