About Password Strength Checker
Our password strength checker uses the industry-standard zxcvbn library developed by Dropbox to analyze password security. This advanced algorithm evaluates passwords based on pattern matching, dictionary attacks, spatial patterns (keyboard walks), repeats, sequences, and common substitutions. All analysis happens locally in your browser - your passwords never leave your device or get transmitted to any server.
How Password Strength is Measured
Password strength is measured using multiple sophisticated techniques. The zxcvbn library analyzes your password for common patterns including dictionary words, names, common passwords from breach databases, keyboard patterns (like "qwerty"), sequential characters (like "abc123"), repeated characters, dates, and years. It calculates the number of guesses an attacker would need to crack your password using various attack methods, providing realistic crack time estimates for different scenarios.
Understanding the Scoring System
Passwords are scored on a scale from 0-4, which we convert to a percentage (0-100%) for easier understanding:
- 0 (Very Weak): Extremely easy to crack - avoid at all costs
- 1 (Weak): Too guessable - risky for any account
- 2 (Fair): Somewhat guessable - acceptable only for low-risk accounts
- 3 (Good): Safely unguessable - good for most accounts
- 4 (Strong): Very unguessable - excellent for critical accounts
What Makes a Password Weak?
- Short Length: Passwords under 12 characters are vulnerable to brute-force attacks, even with good character variety.
- Common Passwords: Using passwords like "password123", "qwerty", or "letmein" that appear in breach databases and common password lists.
- Dictionary Words: Single words or common phrases are easily cracked by dictionary attacks, even with number/symbol substitutions (like "P@ssw0rd").
- Sequential Patterns: Sequences like "123456", "abcdef", or keyboard walks like "qwertyuiop" are highly predictable.
- Repeated Characters: Patterns like "aaaaaa", "111111", or "ababab" have very low entropy and are easily guessed.
- Personal Information: Names, birthdays, addresses, phone numbers, or other personal data are easily guessed through social engineering.
- Dates and Years: Common date formats and years (especially birth years) are frequently tested by attackers.
- Lack of Character Variety: Using only lowercase letters, only numbers, or limited character types significantly reduces password space.
Understanding Crack Time Estimates
Our checker provides four different crack time scenarios based on realistic attack speeds:
Online Attack (Throttled) - 100 attempts/hour
Represents attacks against live login systems with aggressive rate limiting. Most secure websites implement throttling to slow down attackers, allowing only a limited number of login attempts per hour. This is the most realistic scenario for attacks against active web services.
Online Attack (No Throttling) - 10 attempts/second
Represents attacks against systems with minimal or no rate limiting. Some older systems or poorly configured services may allow rapid-fire login attempts. This scenario is less common but still relevant for certain targets.
Offline Attack (Slow Hashing) - 10,000 attempts/second
Represents attacks on stolen password hashes that use strong hashing algorithms like bcrypt, scrypt, or Argon2. These algorithms are specifically designed to be slow and computationally expensive, making offline cracking much harder. This scenario applies when a database is breached but uses proper password hashing.
Offline Attack (Fast Hashing) - 10 billion attempts/second
Represents attacks on stolen password hashes using weak or outdated hashing algorithms like MD5 or SHA1, or when passwords are stored with insufficient protection. Modern GPUs and specialized hardware can test billions of passwords per second against these weak hashes. This is the worst-case scenario when databases are breached with poor security practices.
Pattern Detection
The zxcvbn library identifies various patterns in your password that make it weaker:
- Dictionary: Common words from English and other languages
- Spatial: Keyboard patterns like "qwerty" or "asdfgh"
- Repeat: Repeated characters or patterns like "aaa" or "123123"
- Sequence: Sequential characters like "abc" or "789"
- Date: Common date formats and years
- Common: Frequently used passwords from breach databases
How to Create Strong Passwords
1. Increase Length
Length is the most important factor in password strength. Each additional character exponentially increases the number of possible combinations. Aim for at least 12-16 characters for standard accounts and 20+ characters for critical accounts like email, banking, or password managers.
2. Use Character Variety
Mix uppercase letters, lowercase letters, numbers, and special symbols (!@#$%^&*). This expands the character set and makes brute-force attacks exponentially harder. However, don't rely solely on character variety - length is more important.
3. Avoid Patterns and Predictability
Don't use sequential characters (abc, 123), repeated patterns (ababab), keyboard walks (qwerty), or common substitutions (P@ssw0rd). These patterns are well-known to attackers and significantly weaken your password despite appearing complex.
4. Use Random Generation
Let a password manager or generator create truly random passwords. Human-created passwords tend to follow predictable patterns. Random generation ensures maximum entropy and unpredictability.
5. Consider Passphrases
Use multiple random words separated by special characters (like "correct-horse-battery-staple"). Passphrases are easier to remember than random character strings while maintaining high security. Use 4-6 random words for best results.
6. Avoid Personal Information
Never use names, birthdays, addresses, phone numbers, or other personal information that could be discovered through social media or public records. Attackers often try these first.
7. Use Unique Passwords
Never reuse passwords across different accounts. If one account is breached, all accounts with the same password become vulnerable. Use a password manager to generate and store unique passwords for every account.
Password Manager Recommendations
Using a password manager is the best way to maintain strong, unique passwords for all your accounts:
- Bitwarden: Open-source, free tier available, excellent security
- 1Password: User-friendly, great family plans, strong security features
- LastPass: Popular choice, free tier available, cross-platform
- KeePass: Completely offline, open-source, maximum control
- Dashlane: Intuitive interface, built-in VPN, dark web monitoring
Two-Factor Authentication (2FA)
Even the strongest password can be compromised through phishing, keylogging, or database breaches. Always enable two-factor authentication (2FA) when available. 2FA adds an additional layer of security by requiring a second form of verification:
- Authenticator Apps: Google Authenticator, Authy, Microsoft Authenticator (most secure)
- Hardware Keys: YubiKey, Google Titan (highest security for critical accounts)
- SMS Codes: Less secure than apps but better than nothing
- Backup Codes: Always save backup codes in a secure location
Common Password Myths
Myth: Changing passwords frequently makes them more secure
Reality: Frequent password changes often lead to weaker passwords as users make minor, predictable modifications (like adding a number). It's better to use a strong, unique password and change it only if you suspect a breach or the service has been compromised.
Myth: Complex character substitutions make passwords uncrackable
Reality: Common substitutions like "@" for "a" or "0" for "o" are well-known to attackers and don't significantly improve security. "P@ssw0rd" is just as weak as "Password". True randomness is more important than perceived complexity.
Myth: Longer passwords are always harder to remember
Reality: Passphrases made of random words can be both long and memorable. "correct-horse-battery-staple" is easier to remember than "xK9#mP2$" and significantly more secure.
Myth: Password strength checkers steal your passwords
Reality: Reputable password strength checkers (like this one) perform all analysis locally in your browser using JavaScript. Your password never leaves your device. Always verify that the checker runs client-side.
When to Check Password Strength
- Before setting a new password for any important account
- When conducting security audits of existing passwords
- After manually creating a password to verify its strength
- When teaching others about password security
- To understand why certain passwords are rejected by systems
- When comparing different password strategies or generators
- Before storing passwords in a password manager
Frequently Asked Questions
Is it safe to check my real password here?
Yes, completely safe. All password analysis happens locally in your browser using JavaScript. Your password never leaves your device, is never transmitted over the internet, and is never stored anywhere. You can verify this by checking your browser's network tab - no data is sent to any server. However, as a general security practice, we recommend testing similar passwords rather than your actual passwords.
What's a good password strength score?
Aim for a score of 3 (Good) or 4 (Strong) for most accounts. Critical accounts like email, banking, and password managers should always have a score of 4 (Strong). Scores of 0-1 are unacceptable for any account, and a score of 2 (Fair) should only be used for low-risk accounts that don't contain sensitive information.
Why does my long password show as weak?
Length alone isn't enough if your password contains common patterns, dictionary words, or predictable sequences. For example, "passwordpasswordpassword" is long but extremely weak because it's a repeated common word. Similarly, "abcdefghijklmnop" is long but weak due to the sequential pattern. True strength comes from both length and randomness.
How often should I change my passwords?
Change passwords immediately if you suspect a breach, receive a security notification, or if a service you use has been compromised. Otherwise, strong, unique passwords don't need frequent changes. Focus on using unique passwords for each account rather than changing them regularly. Enable breach monitoring through services like Have I Been Pwned to know when to change passwords.
What's the difference between this and other password checkers?
This checker uses zxcvbn, an industry-standard library developed by Dropbox that's used by major companies worldwide. Unlike simple checkers that only count character types, zxcvbn performs sophisticated pattern matching and realistic attack simulations. It provides accurate crack time estimates based on real-world attack scenarios rather than theoretical calculations.
Can I use this checker for my organization's password policy?
Yes! The zxcvbn library is widely used in enterprise environments. You can integrate it into your systems to enforce strong password requirements. The library is open-source and available on GitHub. Consider requiring a minimum score of 3 for standard accounts and 4 for privileged accounts.
Additional Security Resources
- Have I Been Pwned: Check if your email or password has been compromised in data breaches
- NIST Password Guidelines: Official recommendations from the National Institute of Standards and Technology
- EFF Dice-Generated Passphrases: Method for creating strong, memorable passphrases using dice
- Privacy Guides: Comprehensive guides for digital security and privacy
- OWASP Authentication Cheat Sheet: Best practices for authentication security