Password Strength Checker - Test Your Password Security
Analyze your password strength with our free online password tester. Get instant feedback on password security, entropy calculation, estimated crack time, and detailed recommendations to improve your password.
Instant Analysis
Real-time password strength analysis as you type with detailed security metrics.
Entropy Calculation
Calculate password entropy in bits to measure true randomness and unpredictability.
Crack Time Estimate
See how long it would take to crack your password using brute force attacks.
Enter Password to Check
What is Password Strength?
Password strength is a measure of how difficult it is for an attacker to guess or crack your password. A strong password is one that is long, complex, and unpredictable, making it resistant to various attack methods including brute force, dictionary attacks, and rainbow table attacks.
Our password strength checker analyzes multiple factors including length, character variety, entropy, common patterns, and known weak passwords to give you an accurate assessment of your password's security.
How Password Strength is Calculated
1. Length
Password length is the most important factor. Each additional character exponentially increases the number of possible combinations, making the password harder to crack.
2. Character Variety
Using different character types (uppercase, lowercase, numbers, symbols) increases the character set size, which dramatically increases password complexity.
3. Entropy
Entropy measures the randomness and unpredictability of a password. Higher entropy means more possible combinations and better security. It's calculated as log₂(charset^length).
4. Pattern Detection
Our checker identifies common patterns like sequential characters (abc, 123), repeated characters (aaa, 111), and keyboard patterns (qwerty) that weaken passwords.
5. Common Password Check
We check against known common passwords and dictionary words that are easily guessed by attackers.
Understanding Crack Time Estimates
The "time to crack" estimate shows how long it would take an attacker to guess your password using brute force methods. This assumes an attacker can make 1 billion guesses per second, which is achievable with modern hardware and GPU clusters.
| Crack Time | Security Level | Recommendation |
|---|---|---|
| Instantly - Minutes | Very Weak | Change immediately |
| Hours - Days | Weak | Needs improvement |
| Months - Years | Moderate | Acceptable for low-risk accounts |
| Centuries+ | Strong | Excellent security |
What Makes a Strong Password?
✓ Strong Password Characteristics
- • At least 12-16 characters long
- • Mix of uppercase and lowercase letters
- • Includes numbers and symbols
- • No dictionary words or names
- • No personal information
- • Unique for each account
- • Random and unpredictable
✗ Weak Password Characteristics
- • Short (less than 8 characters)
- • Only letters or only numbers
- • Common words or phrases
- • Personal information (birthdays, names)
- • Sequential patterns (123, abc)
- • Repeated characters (aaa, 111)
- • Keyboard patterns (qwerty, asdf)
Common Password Attack Methods
Brute Force Attack
Attackers try every possible combination of characters until they find the correct password. Longer passwords with more character variety are exponentially harder to crack.
Dictionary Attack
Attackers use lists of common words, phrases, and known passwords. This is why using dictionary words or common passwords is dangerous.
Rainbow Table Attack
Pre-computed tables of password hashes are used to quickly reverse-engineer passwords. This is why unique, complex passwords are important.
Credential Stuffing
Attackers use leaked username/password combinations from data breaches to try accessing other accounts. This is why password reuse is extremely dangerous.
How to Improve Your Password Strength
- Increase Length: Add more characters. A 16-character password is significantly stronger than a 12-character one.
- Add Character Variety: Include uppercase, lowercase, numbers, and symbols to expand the character set.
- Avoid Patterns: Don't use sequential characters, repeated characters, or keyboard patterns.
- Remove Dictionary Words: Replace common words with random character combinations.
- Use a Password Generator: Let a tool create truly random passwords for maximum security.
- Enable 2FA: Add two-factor authentication as an extra security layer.
Frequently Asked Questions
Is it safe to check my password on this website?
Yes. All password analysis happens locally in your browser using JavaScript. Your password is never sent to our servers or stored anywhere. You can verify this by checking your browser's network activity.
What is password entropy?
Entropy is a measure of password randomness and unpredictability, expressed in bits. Higher entropy means more possible combinations. A password with 60+ bits of entropy is considered strong.
How accurate is the crack time estimate?
Our estimates assume an attacker can make 1 billion guesses per second, which is realistic with modern hardware. However, actual crack time depends on the attack method, hardware used, and whether the password hash is salted.
Should I change my password if it shows as weak?
Yes, absolutely. If your password is rated as weak or fair, you should change it immediately to a stronger password. Use our password generator to create a secure replacement.