Password Strength Checker

Analyze your password's strength, entropy, and estimated crack time. Get specific suggestions to make it stronger. Your password never leaves your browser.

Enter Password

Enter a password to check its strength

Characters

Entropy (bits)

0/5

Score

—

Est. Crack Time

Criteria

✓ At least 12 characters

✓ Uppercase letters (A–Z)

✓ Lowercase letters (a–z)

✓ Numbers (0–9)

✓ Special characters (!@#$...)

✓ No long repeated patterns

✓ Not a common password

✓ 16+ characters (excellent)

Suggestions

Enter a password above to receive personalized suggestions.

About Password Strength Checker

This tool analyzes your password locally in your browser — it is never transmitted to any server. It checks length, character variety, entropy (randomness), and known weak patterns to give you an accurate strength assessment and actionable improvement tips.

What Makes a Strong Password?

A strong password is long (16+ characters), uses a mix of character types (uppercase, lowercase, numbers, symbols), avoids dictionary words, and contains no predictable patterns like "123" or "aaa".

Frequently Asked Questions

Yes. The password is analyzed entirely in your browser using JavaScript. It is never sent to any server, never logged, and never stored anywhere. You can verify this by disconnecting from the internet and the tool will still work perfectly.

Entropy measures the unpredictability (randomness) of a password in bits. It's calculated as log₂(character_pool_size^length). Higher entropy means more possible combinations for an attacker to guess. 50+ bits is good; 80+ bits is strong; 100+ bits is excellent.

Crack time is estimated based on entropy and assumes an offline brute-force attack at 10 billion guesses per second — the speed of a modern GPU cluster. Online attacks are much slower (100–1000 guesses/second) due to rate limiting.

A strong password is hard to guess or crack. A secure password is also unique (not reused across sites), stored safely (in a password manager), and changed if the site it was used on suffers a data breach. Strength is necessary but not sufficient for security.