Password Strength Checker
Free online password strength checker. No sign-up, no installation. Runs entirely in your browser.
🔒 Your password never leaves your device. All calculations happen locally in your browser.
What is Password Strength?
Password strength measures how resistant a password is to being guessed or cracked through automated attacks. A strong password is difficult to predict and uses a combination of character types and sufficient length.
This checker analyzes your password against multiple factors:
- Length: Longer passwords are exponentially harder to crack
- Character Variety: Mix of uppercase, lowercase, numbers, and symbols increases complexity
- Pattern Detection: Identifies keyboard walks, sequential characters, and common words
- Entropy: Measures the randomness and unpredictability of your password
How to Use This Tool
- Type or paste a password into the input field above
- Watch the strength meter update in real-time as you type
- Review the feedback and statistics to understand your password's security
- Follow the suggestions to improve your password strength if needed
- Remember: Never use the same password across multiple websites
Understanding Strength Levels
Frequently Asked Questions
How does this tool estimate time to crack?
The tool estimates time to crack based on offline attacks, assuming 1 billion guesses per second. This is a conservative estimate. Online attacks (against websites with rate limiting) would be much slower. The actual time depends on the attacker's resources and the security measures in place.
Is my password sent to any server?
No. This tool runs entirely in your browser. Your password is never sent anywhere. All calculations happen locally on your device. You can even disconnect from the internet and the tool will continue to work.
What makes a password strong?
A strong password typically has: at least 12 characters, a mix of uppercase and lowercase letters, numbers, and special symbols, no dictionary words or keyboard patterns, and no personal information (names, birthdays). Avoid using predictable substitutions like "P@ssw0rd" which contains common patterns.
Should I use the same password everywhere?
Absolutely not. Using the same password across multiple websites means that if one service is compromised, attackers can access all your accounts. Use unique, strong passwords for each important account. Consider using a password manager to securely store your passwords.
What's the difference between entropy and strength?
Entropy measures how many possible combinations your password represents, in bits. This tool computes it as length x log2(character-set size), where the character set is derived from what the password actually contains: 26 for lowercase, 26 for uppercase, 10 for digits, 32 for ASCII symbols, 1 for whitespace, and 3,500 for non-ASCII characters such as Chinese, Japanese or Korean. That 3,500 is deliberately conservative — roughly the number of Chinese characters in everyday use, not the 20,000+ in the Unicode CJK block. Strength is a simplified rating (Very Weak to Very Strong) combining entropy, length and pattern penalties, so high entropy alone does not guarantee a high rating. Also be clear about the limits of this estimate: it measures the size of the character-set search space, minus penalties for a few obvious regularities (common words, keyboard runs, dates, whole-password repetition and fixed periods). Near-regular passwords such as abcabd, or any meaningful sentence, will still be guessed far faster than the number on screen suggests. For real security, use a password manager to generate a random password. Honest note: before 2026-07-26 the character set only covered the four ASCII classes, so a Chinese password produced a character set of zero, log2 of zero, an entropy readout of 0, and a crack-time estimate of "Less than 1 second" for a thirteen-character passphrase.
Can I use spaces and special Unicode characters?
Yes, and this tool now scores them properly: spaces and non-ASCII characters (Chinese, Japanese, Korean, accented Latin, emoji) all count towards length and character-set size. One CJK character contributes roughly as much entropy as two random alphanumeric characters. Two caveats worth stating plainly. First, many websites only accept ASCII, so check your service's requirements before relying on this. Second, the entropy figure assumes random selection — a password that is a meaningful sentence in any language is far weaker than the number suggests, because an attacker can guess whole phrases from a corpus rather than brute-forcing character by character.