Analyze your password's strength, entropy, and estimated crack time. Get specific suggestions to make it stronger. Your password never leaves your browser.
Enter a password to check its strength
0
Characters
0
Entropy (bits)
0/5
Score
-
Est. Crack Time
Criteria
✓ At least 12 characters
✓ Uppercase letters (A–Z)
✓ Lowercase letters (a–z)
✓ Numbers (0–9)
✓ Special characters (!@#$...)
✓ No long repeated patterns
✓ Not a common password
✓ 16+ characters (excellent)
Suggestions
Enter a password above to receive personalized suggestions.
About Password Strength Checker
This tool analyzes your password locally in your browser - it is never transmitted to any server. It checks length, character variety, entropy (randomness), and known weak patterns to give you an accurate strength assessment and actionable improvement tips.
What Makes a Strong Password?
A strong password is long (16+ characters), uses a mix of character types (uppercase, lowercase, numbers, symbols), avoids dictionary words, and contains no predictable patterns like "123" or "aaa".
Frequently Asked Questions
Yes. The password is analyzed entirely in your browser using JavaScript. It is never sent to any server, never logged, and never stored anywhere. You can verify this by disconnecting from the internet and the tool will still work perfectly.
Entropy measures the unpredictability (randomness) of a password in bits. It's calculated as log₂(character_pool_size^length). Higher entropy means more possible combinations for an attacker to guess. 50+ bits is good; 80+ bits is strong; 100+ bits is excellent.
Crack time is estimated based on entropy and assumes an offline brute-force attack at 10 billion guesses per second - the speed of a modern GPU cluster. Online attacks are much slower (100–1000 guesses/second) due to rate limiting.
A strong password is hard to guess or crack. A secure password is also unique (not reused across sites), stored safely (in a password manager), and changed if the site it was used on suffers a data breach. Strength is necessary but not sufficient for security.
About Password Strength Checker — Password Strength Checker Online
A password strength checker online evaluates your password against multiple security criteria — length, character variety, entropy, and common weakness patterns — and tells you in real time how strong it is and how long it would take an attacker to crack it. Security-conscious users, developers auditing default credentials, IT administrators, and anyone creating a new account for an important service use a password strength checker online to make an informed decision about their password choices before committing to them.
This tool goes beyond simple "weak / medium / strong" labels. It calculates actual Shannon entropy in bits, estimates crack time based on a modern GPU-speed brute-force attack at 10 billion guesses per second, checks against a list of the most commonly used passwords, and provides specific, actionable suggestions — not just a color-coded bar. Most importantly, your password never leaves your device. The entire analysis runs locally in your browser, making it safe to check real passwords that you actually use or plan to use.
How to Use the Password Strength Checker
Type or paste your password into the Enter Password field. The analysis begins instantly as you type — no button press required.
Watch the strength bar and label update in real time: Very Weak, Weak, Fair, Strong, or Very Strong.
Check the stats panel for your password's character count, entropy in bits, score out of 5, and estimated crack time.
Review the Criteria checklist to see exactly which requirements your password meets and which it does not — at least 12 characters, uppercase, lowercase, numbers, special characters, no repeated patterns, and not a common password.
Read the Suggestions list for specific, personalized recommendations on how to improve the password. Click the eye icon to toggle between showing and hiding the password as you type.
What the Password Strength Checker Analyzes
This password strength checker online evaluates several distinct dimensions of password security, giving you a complete picture rather than a single oversimplified rating.
Length: Password length is the single most important factor in security. Each additional character multiplies the number of possible combinations by the character pool size. The checker flags passwords below 12 characters as failing the minimum threshold and awards a bonus point for passwords at 16 characters or more.
Character variety: Using all four character classes — uppercase letters, lowercase letters, digits, and special characters — dramatically increases the search space for brute-force attacks. The checker tracks each class independently and awards a point for having both uppercase and lowercase, a point for digits, and a point for special characters.
Entropy: Entropy (measured in bits) quantifies the theoretical unpredictability of the password. It is calculated as the password length multiplied by the log base 2 of the character pool size. 50+ bits is adequate; 80+ bits is strong; 100+ bits is excellent for most purposes.
Pattern and repetition detection: Passwords containing three or more consecutive identical characters (like "aaa") are flagged. Predictable patterns significantly reduce effective entropy even when other criteria are met.
Tips for Getting the Best Results
Use these guidelines alongside the password strength checker online to create passwords that are both secure and practical.
Length beats complexity: A 20-character password made entirely of lowercase letters has more entropy than an 8-character password with uppercase, numbers, and symbols. Prioritize length above all other factors. Aim for at least 16 characters for any account that matters.
Use passphrases for memorability: Four or more random, unrelated words strung together — such as "correct horse battery staple" — are both highly secure (high entropy from length) and far easier to remember than a scrambled mix of characters. The checker will rate a long passphrase as Very Strong.
Avoid predictable substitutions: Replacing letters with similar-looking numbers (e for 3, a for @, i for 1) is well-known to attackers. These substitutions are built into cracking dictionaries and add far less security than they appear to. The checker accounts for this in its overall score.
Never reuse passwords across sites: Even a very strong password becomes a liability if it is reused. If one site suffers a data breach, attackers will try your leaked password on every other service. A password manager generates and stores unique passwords for every site automatically.
Test candidate passwords before adopting them: Use this tool to evaluate password ideas before you commit to using them. Aim for a score of 4–5 and an entropy of at least 80 bits. The suggestions list will guide you on exactly what to change if the score falls short.
Why Use a Password Strength Checker Online
A browser-based password strength checker online works instantly without installing any app. Because the analysis is entirely client-side, the tool is inherently private — there is no backend to log your input, no database to breach, and no account to create. You get an honest, technical assessment of your password security based on real cryptographic metrics rather than vague marketing language about "strong" passwords.
This tool is valuable for individuals creating passwords for banking or email accounts, for developers testing the passwords their users might choose, for security awareness trainers demonstrating why short passwords fail, and for IT teams that need a quick way to evaluate password policy compliance without installing software.
Frequently Asked Questions about Password Strength Checker
Absolutely not. Your password is analyzed entirely in your browser using JavaScript and never transmitted to any server, never logged, and never stored in any way. You can verify this by disconnecting from the internet — the tool continues to work because no network requests are involved in the analysis. It is completely safe to test real passwords you actually use or plan to use.
Security experts and major standards bodies like NIST recommend at least 16 characters for important accounts. Longer passwords are exponentially harder to crack because each additional character multiplies the number of possible combinations by the full character pool size. A randomly generated 20-character password is astronomically more secure than a complex but short 8-character one, regardless of how many special characters the short one contains.
Often yes. A phrase like "correct-horse-battery-staple" at 28 characters is both highly memorable and extremely difficult to brute-force because of its length, while a typical complex 8-character password like "P@ss123!" scores Weak due to its short length. Passphrases work best when you choose words at random rather than meaningful phrases that relate to you personally.
Yes, highly recommended. Password managers like Bitwarden, 1Password, and Dashlane generate cryptographically random, unique passwords for every website and store them securely. You only need to remember one strong master password. This solves the password reuse problem entirely and makes it practical to have 100+ unique strong passwords across all your accounts.
Entropy, measured in bits, quantifies how unpredictable a password is. It is calculated based on the size of the character pool used and the password length. Higher entropy means more possible combinations an attacker must search through. Generally, 50+ bits is adequate for low-risk accounts, 80+ bits is strong, and 100+ bits is excellent. The checker displays this value so you can see the raw security metric rather than just a label.
Yes, completely free. There are no sign-up requirements, usage limits, or premium features. You can check as many passwords as you like at no cost, with no ads tracking your input.
Yes. The tool is fully responsive and works on smartphones and tablets. The password field, strength bar, criteria checklist, and suggestions all display correctly on narrow screens. You can test passwords from your mobile browser without installing any app.
The crack time is calculated by dividing the total number of possible combinations (2 to the power of the entropy in bits) by an assumed attack rate of 10 billion guesses per second — the approximate speed of a modern high-end GPU cracking cluster in an offline attack scenario. Real-world online attacks are much slower due to rate limiting, but this conservative assumption gives you the worst-case security estimate.