Password Strength Checker

Analyze password strength with entropy calculation, crack time estimation, and security suggestions. Check for common passwords and weak patterns.

Check your password strength with entropy calculation and security analysis

StrengthEnter password to check...
All analysis happens locally in your browser. Your password is never sent to any server. Crack time estimates assume a powerful GPU cluster (10 billion guesses/second).

How to Use This Tool

  1. 1

    Enter your password

    Type or paste the password you want to analyze. Click the eye icon to toggle visibility.

  2. 2

    View strength rating

    The strength meter shows a rating from Very Weak to Very Strong based on entropy calculation.

  3. 3

    Check crack time estimate

    See how long it would take a GPU cluster to crack your password through brute force. Longer is better!

  4. 4

    Follow suggestions

    If your password is weak, follow the improvement suggestions to make it stronger. Aim for at least 'Strong' rating.

Frequently Asked Questions

What is password entropy?
Entropy measures password randomness in bits. Higher entropy = harder to crack. Each additional bit doubles the possible combinations. A 40-bit password has ~1 trillion combinations; 80-bit has ~1 septillion.
How is crack time calculated?
We assume a powerful GPU cluster attempting 10 billion guesses per second. The formula divides total possible combinations by this rate, then halves for average case.
Is my password sent to a server?
No. All analysis happens entirely in your browser using JavaScript. Your password never leaves your device. You can verify by disconnecting from the internet — the tool still works.
What makes a password strong?
Strong passwords are long (12+ characters), use mixed character types (upper, lower, numbers, symbols), avoid dictionary words, and don't follow predictable patterns like 'Password123!'.