Password Strength Checker
Test password strength with real-time entropy calculation, crack time estimation, and security recommendations. 100% browser-based – your password never leaves your device.
Key Features
- Real-Time Analysis – Instant feedback as you type
- Entropy Calculation – Measures password randomness in bits
- Crack Time Estimation – Shows time to crack at various hash rates
- Character Set Detection – Identifies used character types
- Pattern Detection – Identifies common weaknesses
- Breach Database Check – Optional HIBP integration
- Strength Scoring – Visual strength indicator
- Improvement Suggestions – Actionable recommendations
- Privacy First – All analysis done in browser
- No Storage – Password never saved or transmitted
Password Strength Indicators
🔴 Weak
Entropy: < 35 bits
Crack Time: Seconds to minutes
Example: password123
Recommendations:
- Add more characters (12+ minimum)
- Use multiple character types
- Avoid common words/patterns
🟡 Moderate
Entropy: 35-59 bits
Crack Time: Hours to months
Example: MyP@ssw0rd!
Recommendations:
- Increase length to 16+ characters
- Avoid predictable substitutions
- Use random generation
🟢 Strong
Entropy: 60+ bits
Crack Time: Years to centuries
Example: xK9#mP2$vL7&qR3*
Characteristics:
- 16+ random characters
- All character types included
- No predictable patterns
Understanding Entropy
Entropy measures password randomness in bits. Higher entropy = stronger password. Each bit doubles the number of possible combinations.
Entropy by Character Set
| Character Set | Bits per Character | 12-char Entropy |
|---|---|---|
| Lowercase only (26) | ~4.7 bits | 56 bits |
| Alphanumeric (62) | ~6.0 bits | 72 bits |
| Full ASCII (95) | ~6.6 bits | 79 bits |
💡 Pro Tip: A 12-character password with full ASCII (79 bits) is stronger than a 16-character lowercase password (75 bits)
Common Password Weaknesses
❌ Avoid These
- Dictionary words – “password”, “admin”, “welcome”
- Common patterns – “123456”, “qwerty”, “abc123”
- Personal info – Names, birthdays, addresses
- Simple substitutions – “P@ssw0rd” instead of “Password”
- Keyboard walks – “1qaz2wsx”, “asdfghjkl”
- Repeated characters – “aaaa”, “1111”, “xxxx”
✅ Better Alternatives
- Random generation – Use password generator tools
- Passphrases – “correct-horse-battery-staple”
- Long passwords – 16+ characters minimum
- True randomness – No predictable patterns
- Unique passwords – Different for each account
- Password managers – Store securely, generate randomly
Frequently Asked Questions
Is it safe to test my password online?
Yes, if using client-side tools. Our tool analyzes passwords entirely in your browser – nothing is sent to any server. The password never leaves your device.
What is password entropy?
Entropy measures password unpredictability in bits. It’s calculated based on:
- Password length
- Character set size (lowercase, uppercase, numbers, symbols)
- Randomness (patterns reduce entropy)
Higher entropy = more secure password. Target 60+ bits for important accounts.
How accurate are crack time estimates?
Crack time estimates assume:
- Brute force attack – Trying every possible combination
- Average case – Found at 50% of keyspace
- Hash rate – Based on modern GPU/cloud computing
Actual crack times vary based on hashing algorithm, hardware, and attack method.
Should I check if my password has been breached?
Yes! Use services like Have I Been Pwned to check if your password appears in known data breaches. If breached, change it immediately.
Our tool can integrate with HIBP’s API using k-anonymity – only the first 5 characters of your password hash are sent, protecting your full password.
What makes a password “strong”?
A strong password has:
- Length – Minimum 12 characters, prefer 16+
- Randomness – No predictable patterns
- Character variety – Mix of uppercase, lowercase, numbers, symbols
- Uniqueness – Not used elsewhere
- Not breached – Not in known breach databases
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