Password Strength Checker – Test Security & Crack Time Free
About the Password Strength Checker
The Password Strength Checker analyzes any password in real time, scoring it against six security requirements and calculating its entropy and estimated time to crack at 10 billion guesses per second. A live strength meter and checklist show exactly what’s missing, whether that’s length, uppercase letters, numbers, or special characters.
It’s built for anyone auditing an existing password before reusing it, rather than generating a brand-new one. If you need a fresh, high-entropy password instead of testing one you already have, the Password Generator creates one instantly, and once you have it, this checker can confirm exactly how strong it is.
The BigToolSite Team tested this checker against passwords of varying length and character variety, including common weak patterns and 20-character random strings, to confirm the entropy and crack-time estimates scale correctly.
How to Use the Password Strength Checker
- Type or paste a password into the input field — nothing is sent anywhere, analysis happens instantly in your browser.
- Check the Security Strength meter and label, from Very Weak to Very Strong.
- Review the Requirements Checklist to see which criteria your password meets.
- Check Time to Crack and Password Entropy for a technical view of its resistance to brute-force attacks.
- Click Generate Strong Password if you’d rather start fresh with a secure 20-character password.
Example Usage
Input: password123
Output: Strength: Weak, missing uppercase and special characters, low entropy, crack time under a few hours.
Add uppercase letters, a symbol, and extend it past 12 characters, and the same password jumps to “Very Strong” with a crack time measured in centuries.
Frequently Asked Questions
No, all analysis happens directly in your browser using JavaScript. Your password is never transmitted or stored.
Entropy measures the mathematical randomness of a password in bits, based on its length and the variety of character types used. Higher entropy means more possible combinations to guess.
It’s estimated using an assumed brute-force rate of 10 billion guesses per second, a common benchmark for modern password-cracking hardware.
A password needs at least 12 characters, uppercase and lowercase letters, numbers, special characters, and sufficiently high entropy to reach the top strength tier.
Yes, it’s completely free with no signup required.
