What is Password Entropy?
Password entropy is a measurement of how unpredictable a password is. It's measured in bits and is calculated based on the length of the password and the size of the character pool used (lowercase letters, uppercase letters, numbers, and symbols).
A higher entropy means the password would take significantly longer for an attacker to crack using brute-force methods. For example, a 12-character password using only lowercase letters has an entropy of about 56 bits, while an 8-character password using letters, numbers, and symbols has an entropy of about 52 bits.
How is Cracking Time Estimated?
Our analyzer estimates the time it would take to crack your password offline using modern hardware. We assume an attacker can make 100 billion guesses per second, which is typical for modern GPU clusters targeting fast hashing algorithms (like MD5 or SHA-1) without proper salting and key stretching (like bcrypt or Argon2).
If your password protects a system that enforces rate limiting (e.g., locking out after 5 failed attempts), brute-forcing online is impossible. However, if a database is breached, attackers can perform offline cracking at the speeds estimated above.
Is this Tool Secure?
Yes. This password entropy analyzer runs entirely within your web browser using JavaScript. No data is sent to our servers or stored anywhere. You can even disconnect your internet connection, refresh the page, and the tool will continue to work perfectly.
Best Practices for Secure Passwords
- Length is key: A long password (14+ characters) is generally stronger than a short, complex one.
- Use passphrases: A sequence of random words (e.g.,
correct horse battery staple) is easy to remember but hard to crack. - Avoid common patterns: Do not use dictionary words, sequential numbers (123456), or common substitutions (P@ssw0rd).
- Use a password manager: The most secure password is one you don't even know. Let a password manager generate and store complex passwords for you.