How Password Entropy & Strength Auditing Works
How do you know if your password is truly strong? Counting characters or checking for uppercase letters isn't enough. Security professionals measure password resistance using entropy (measured in bits), which calculates the exact mathematical randomness of your password against brute-force cracking algorithms.
A password with less than 28 bits of entropy can be cracked in seconds. A password with 60+ bits takes centuries for high-speed GPU clusters to test. Our local password checker analyzes character pool size, length, and common dictionary patterns to calculate your exact bit entropy and estimated crack times under different attack speeds.
100% Offline & Private: Testing your real password on third-party websites is a huge security risk. Our audit tool runs 100% locally inside your browser's JavaScript engine. Not a single keystroke is ever sent over the network or saved in a database.
Password Length & Brute-Force Cracking Time Benchmark
| Length | Numbers Only | Lowercase Only | Mixed All (Upper+Lower+Digits+Symbols) | Security Level |
|---|---|---|---|---|
| 6 chars | < 1 ms | < 1 sec | 5 secs | Weak |
| 8 chars | < 1 sec | 3 mins | 8 hours | Medium |
| 12 chars | 3 secs | 3 weeks | 34,000 Years | Strong |
| 16 chars | 1 hour | 100,000 Years | 10+ Billion Years | Excellent |
| 20+ chars | 500+ Years | ∞ | ∞ (Uncrackable) | Uncrackable |
Frequently Asked Questions
How long should a secure password be?
Security experts recommend at least 12 to 16 characters. Every extra character multiplies the number of possible combinations, making brute-force attacks dramatically harder. Our generator supports lengths from 8 to 64 characters.
Is this tool safe to use?
Yes. Passwords are generated with PHP's cryptographically secure random_int function and are never stored or sent to any third party. The password checker in the "Check" tab runs 100% locally in your browser, so nothing you type ever leaves your device.
What makes a password strong?
Three things: length, variety, and randomness. Combine uppercase and lowercase letters, numbers and symbols, and avoid personal information or common words. The built-in strength meter shows entropy in bits and an estimated crack time.
Why shouldn't I reuse the same password everywhere?
If one website suffers a data breach, attackers immediately try that password on your other accounts. Using a unique random password for every site limits the damage of a single leak. Use the history panel to keep track of the passwords you generate.
How is password entropy and crack time calculated?
Entropy measures unpredictability in bits using the formula E = L * log2(R), where L is the character length and R is the pool size (94 possible characters for full ASCII). A password with 80+ bits of entropy requires millions of years to crack even against massive supercomputer clusters and distributed GPU rigs.
What is the difference between a password and a passphrase?
A password is a random string of mixed characters (e.g. 9k#P!z7$Wq), ideal for password managers. A passphrase is a sequence of 4 to 8 random dictionary words separated by hyphens or spaces (e.g. correct-horse-battery-staple), making it extremely strong yet effortless for humans to memorize for master accounts.