How to use Password Strength Checker
This is the Password Strength Checker utility. 100% client-side and offline capable.
Password Strength Checker
Password Strength Analyzer
Evaluate security, entropy & attack resistance - 100% private & offline
Client-Side Only
No Storage
Overall Strength
Enter a password
Very Weak
Weak
Fair
Strong
Excellent
0
Security Score
out of 100
0
bits
Entropy
0
chars
Length
0
pool
Character Set
Security Checks
Not AnalyzedCharacter Types
Lowercase (a-z)
Uppercase (A-Z)
Numbers (0-9)
Symbols (!@#$%)
Pattern Detection
Min Length (12+)
No Repeated Chars
No Sequences
Not in Dictionary
Estimated Crack Time
Online Attack
1,000 guesses/sec (rate-limited)
Instantly
Offline Attack (GPU)
100 billion guesses/sec
Instantly
Supercomputer
100 trillion guesses/sec
Instantly
Understanding Entropy
Entropy measures password randomness in bits using log₂(charset^length)
<40Weak
40-60Fair
60-80Strong
80+Excellent
Password Security Tips
Length Over Complexity
A 16-character passphrase like "correct-horse-battery" is stronger than "P@55w0rd!" mathematically.
Avoid Patterns
Attackers check keyboard patterns (qwerty), dates (1990), and leetspeak (p@55) first.
100% Private
This tool runs entirely in your browser. No passwords are ever transmitted or stored.
Common Questions
Is this Password Strength Checker safe to use with my real passwords?
Yes, absolutely. Our tool runs 100% in your browser using client-side JavaScript. Your password never leaves your device, is never transmitted to any server, and is never stored or logged. This makes it the safest way to test your actual passwords.
What is a good password strength score?
Aim for a score of 80 or above (Excellent). Scores between 60-80 are Strong and acceptable for most purposes. Anything below 40 should be improved immediately as it's vulnerable to cracking.
How long should my password be?
A minimum of 12 characters is recommended for standard accounts. For high-security accounts (banking, primary email, password manager), use 16+ characters. Passphrases of 20+ characters provide maximum protection.
What is password entropy and why does it matter?
Entropy measures your password's randomness in bits using the formula: log₂(charset^length). Higher entropy means more possible combinations an attacker must try. For example, 80 bits of entropy means 2^80 (over 1 septillion) possible combinations to check—making brute force attacks practically impossible.
Why is my password marked as weak even though it has special characters?
Special characters alone don't guarantee strength. Our analyzer checks for common patterns like keyboard sequences (qwerty), common word bases (password, admin), year patterns (1990), and leetspeak substitutions (@ for a, 0 for o). A truly strong password avoids all these patterns.
How accurate are the crack time estimates?
Our estimates are based on current real-world attack capabilities and assume pure brute-force methods. We simulate three scenarios: Online attacks (1,000 guesses/sec), Offline GPU (100 billion/sec), and Supercomputer (100 trillion/sec). Actual crack times could be faster if attackers use optimized dictionaries. Treat estimates as best-case scenarios.
Does this tool work offline?
Yes! Once the page is loaded, you can disconnect from the internet and the tool will continue to function perfectly. All password analysis is performed locally in your browser using JavaScript.
Should I use a password manager instead of creating my own passwords?
We strongly recommend using a reputable password manager. They generate truly random passwords that consistently score 100/100 on strength tests, and you only need to remember one master password. Our tool is perfect for testing and evaluating your master password's strength.