Why Use This Tool?
Most people have no idea how strong their password actually is. 'P@ssw0rd!' looks complex but falls to a dictionary attack in seconds, while a simple four-word passphrase can take centuries to crack. This checker measures the real math.
The entropy calculation uses the standard formula: length × log₂(character pool size), adjusted downward for sequential characters, repeated characters, and common password patterns. Estimated crack time assumes a determined attacker trying 10 billion guesses per second.
How It Works
- Type the password you want to analyze — it never leaves your device.
- Read the entropy in bits, the strength label, and the estimated time to crack.
- Follow the specific suggestions to make it stronger.
Password Entropy?
Entropy measures guessability in bits: each character adds log₂(pool size) bits. A 16-character password from a 94-character pool carries about 104 bits — beyond any practical brute-force reach.
Common Use Cases
- Testing new passwords before using them
- Auditing existing password strength
- Teaching users what makes passwords strong
- Verifying password policy compliance
Frequently Asked Questions
How is password entropy calculated?
Entropy = length × log₂(character pool size). A 16-character password using all 94 printable ASCII characters has about 104 bits. The tool adjusts downward for sequential patterns, repeated characters, and dictionary words.
What is time to crack based on?
It assumes an attacker can try 10 billion guesses per second using modern GPU hardware. This is a realistic estimate for online services without rate limiting.
Is my password sent anywhere?
No. Every calculation runs locally in your browser. The password you type never leaves your device — that's the whole point of this tool.
What makes a password 'common'?
The tool checks against a list of the most breached passwords (password, 123456, qwerty, etc.). These fall instantly regardless of added complexity.
Tips & Things to Watch
- A 16-character password from a 94-character pool is about 104 bits — effectively uncrackable.
- Common passwords are detected and flagged regardless of complexity.
- Use the Password Generator tool to create a strong replacement.
- Enable two-factor authentication — a strong password is half the lock.