# Free Password Strength Checker & Secure Password Generator Explore password-strength feedback and estimated guessing times, or generate a random password with custom settings. Estimates depend on assumptions and do not guarantee security. ## Password Strength Checker Enter Password to Test _Type or paste a password..._ Password Generator Length _16_ Character Types A–Z a–z 0–9 !@# Generate Password Copy Custom Dictionary (space-separated)_company names, personal words, domains..._ Words here are treated as known to attackers, reducing estimated strength. ### Security Analysis Enter a password to see detailed analysis Crack time estimates, strength score, and security feedback will appear here. 100% Private Never sent to any server Crack Time Estimates 4 attack scenarios Password Generator Customizable & secure Pattern Analysis Feedback on common patterns ### What Is a Password Strength Checker? A **password strength checker** offers feedback on patterns that may make a password easier to guess. It is useful for learning why a long, unique, randomly generated password is generally preferable to a familiar phrase or a reused password. The estimates consider patterns such as common words, dates, repeated characters and keyboard sequences. Guessing times use fixed assumptions and are not predictions of an actual attack. For important accounts, generate a unique password and store it in a trusted password manager. To create a fresh password with formatting controls, use the [password generator](https://www.toolcomb.com/password-generator). Never use a UUID as a substitute for a secret: the [UUID generator](https://www.toolcomb.com/uuid-generator) is designed for identifiers. Analysis happens locally in your browser. Prefer testing examples rather than live account passwords; browser extensions, shared devices and clipboard access can still expose sensitive information. #### Score 0 - Very Weak Common passwords, keyboard patterns, or simple words are often easy to guess. #### Score 1 - Weak Common words with simple substitutions or added numbers remain predictable. #### Score 2 - Fair Some patterns remain recognizable; the estimate is not a security guarantee. #### Score 3–4 - Strong Fewer recognized patterns and more guessing resistance under the model's assumptions. ### How to Create a Strong Password - Best Practices ### What Makes a Strong Password - At least 12 characters - 16+ is strongly recommended - Mix of uppercase, lowercase, numbers, and symbols - Random characters - not words, names, or dates - Unique per account - never reuse passwords - No personal information (name, birthday, pet names) - No keyboard patterns (qwerty, asdfgh, 12345) - No common substitutions (@ for a, 3 for e, 0 for o) - Passphrases: 4+ random unrelated words work well ### Common Password Mistakes to Avoid - Using 'password', '123456', or top-10000 common passwords - Adding '1' or '!' to the end of a simple word - Substituting letters with look-alikes (P@ssw0rd) - Using your name, username, or email in the password - Using birth dates, anniversaries, or phone numbers - Using the same password across multiple accounts - Passwords shorter than 8 characters - Using sequential or repeated characters (aaaa, 1234) ### Understanding Password Crack Time Estimates Our tool provides crack time estimates for four real-world attack scenarios. Understanding the difference between these scenarios helps you choose the right password strength for your use case: #### Online (Throttled) - 100 guesses/hour Most online login systems implement rate limiting - locking accounts or requiring CAPTCHAs after 5–10 failed attempts. At 100 guesses per hour, even a weak 6-character password takes days to crack via brute force. This is why common password reuse is dangerous - attackers with leaked password lists don't need to brute force. #### Online (Unthrottled) - 10 guesses/second Some poorly secured systems don't implement rate limiting. At 10 guesses per second, simple passwords fall within minutes to hours. This scenario models APIs, admin panels, or legacy systems that lack proper brute-force protection. #### Offline Slow Hash - 10,000 guesses/second When a database is breached and password hashes are stolen, attackers crack them offline without any rate limits. Slow hashing algorithms (bcrypt, scrypt, Argon2) intentionally slow down cracking to ~10,000 hashes/second. This is why websites should use bcrypt - it makes even moderately strong passwords take years to crack. #### Offline Fast Hash - 10 Billion guesses/second Poorly secured systems use fast hashes (MD5, SHA1, unsalted SHA256) that can be cracked at billions of attempts per second on consumer GPU hardware. At 10 billion/second, an 8-character password with full character set falls in under an hour. This is why MD5 password storage is catastrophically insecure. ### How to Use the Password Generator Our built-in password generator creates cryptographically strong random passwords based on your specifications. Here's how to use it effectively: 1. 1 1. Set Password Length Choose a length between 6 and 128 characters. For most accounts, 16 characters is a good minimum. For high-security accounts (banking, email, password managers), use 20+ characters. 2. 2 2. Select Character Types Check the character types you want included: Uppercase (A–Z), Lowercase (a–z), Numbers (0–9), Symbols (!@#$%^&*). Including all four character types maximizes entropy and strength. Only exclude types if a specific website's rules require it. 3. 3 3. Generate and Review Click 'Generate Password' to create a random password. The strength meter immediately analyzes the generated password. If the strength score is below 3 (Strong), increase the length or add more character types and regenerate. 4. 4 4. Copy to Your Password Manager Click 'Copy' to copy the generated password to your clipboard, then paste it immediately into your password manager (1Password, Bitwarden, Dashlane, LastPass, etc.). Never type generated passwords from memory - that defeats the purpose of random generation. ### Frequently Asked Questions - Password Strength Checker #### Is my password sent to a server when I test it? The checker processes entered text in your browser and does not send it to a server for analysis. Use examples rather than live credentials; extensions, shared devices and clipboard access can still present risks. #### How is password strength calculated? The checker looks for common words, dates, repeated characters and other recognizable patterns, then gives an estimate from 0 to 4. Its guessing-time estimates depend on assumptions and cannot guarantee safety. #### How long should my password be? Security recommendations have evolved significantly. The NIST Special Publication 800-63B (2017) recommends passwords of at least 8 characters, but modern best practice suggests 12–16 characters minimum for typical accounts, and 20+ characters for critical accounts like email, banking, and password managers. Length is the single most impactful factor in password strength - every additional character exponentially increases cracking difficulty. #### Is a 12-character password secure enough? Length helps, but predictability, reuse, the character pool and how a service stores passwords also matter. Prefer a longer randomly generated unique password where supported, and enable multi-factor authentication. #### What is the custom dictionary field for? You can add personal words, names or other predictable terms so the checker can consider them when estimating password strength. It is still an estimate and cannot account for everything an attacker knows. #### Should I use a password manager? Yes - absolutely. Password managers (1Password, Bitwarden, Dashlane, KeePass, Apple Keychain, Google Password Manager) allow you to use a different, fully random password for every account without memorizing them. They also warn you about reused, weak, and compromised passwords. Using our generator to create passwords and storing them in a password manager is the gold standard for personal account security. #### What is entropy in password strength? Entropy is a measure of uncertainty, often expressed in bits. This tool displays an estimated base-10 logarithm of guessing attempts, not measured entropy in bits; it should be treated as an approximate comparison. #### Are passphrases more secure than complex passwords? A passphrase of 4–5 random common words (e.g. 'correct-horse-battery-staple') has high entropy due to length while being more memorable than random character strings. At 20+ characters, a random passphrase can be stronger than a shorter complex password. The key word is 'random' - personally meaningful phrases ('ilovemydog2019') are much weaker than truly random word combinations. ## Related Tools Discover more free tools that might help with your next task. [Base64 Encoder Encode and decode Base64 data Use Tool](https://www.toolcomb.com/base64-encoder) [URL Decoder Decode URL-encoded strings Use Tool](https://www.toolcomb.com/url-decoder) [HTML Encoder Encode and decode HTML entities Use Tool](https://www.toolcomb.com/html-encoder) [Hash Generator Generate MD5, SHA1, SHA256 hashes Use Tool](https://www.toolcomb.com/hash-generator) [UUID Generator Generate v1, v3, v4, and v5 UUIDs Use Tool](https://www.toolcomb.com/uuid-generator) [Password Generator Generate secure random passwords Use Tool](https://www.toolcomb.com/password-generator) ### Related guides Read the how-to, then come back to this tool when you are ready to run it locally. - [How to Generate a Strong Password in the Browser High-entropy passwords generated on-device. Nothing sent to a server.](https://www.toolcomb.com/blog/how-to-generate-a-strong-password-in-the-browser) - [How to Check Password Strength Before You Reuse It Strength analysis in the browser. The password is not stored or transmitted.](https://www.toolcomb.com/blog/how-to-check-password-strength) - [Password Generator vs Password Manager: Random Strings Are Not Storage A generator makes one strong secret. A manager remembers unique secrets per site. Why you still need both, and why an online generator that phones home is the wrong half.](https://www.toolcomb.com/blog/password-generator-vs-password-manager) [View All Tools](https://www.toolcomb.com/tools)