Password Strength Checker — Test Your Password Security

What makes a password strong?

A strong password is long (16+ characters), uses a mix of uppercase and lowercase letters, digits, and special symbols, and avoids common words or patterns. Password length is the single most important factor — each additional character multiplies the number of possible combinations exponentially.

How is password entropy calculated?

Entropy measures how unpredictable a password is, expressed in bits. It is calculated as log2(C^L), where C is the size of the character set used (e.g., 26 for lowercase only, 95 for all printable ASCII) and L is the password length. A higher entropy means a more secure password — aim for at least 60 bits for everyday accounts and 80+ bits for sensitive ones.

How is crack time estimated?

The estimated crack time assumes a brute-force attack at 10 billion guesses per second — a realistic rate for a modern GPU rig attacking offline hashed passwords. The calculation uses the total number of possible combinations divided by 2 (average case) and divided by the guessing speed. Online attacks are far slower, making even shorter passwords relatively safe with rate limiting and lockouts.

Is my password safe to enter here?

Yes. This tool runs entirely in your browser using JavaScript. Your password is never sent to any server, logged, or stored anywhere. You can verify this by checking the network tab in your browser's developer tools — no requests are made while you type.

Best practices for password security

• Use a unique password for every account — never reuse passwords.
• Use a password manager (Bitwarden, KeePass, 1Password) to generate and store passwords.
• Enable two-factor authentication (2FA) wherever possible.
• Prefer passphrases (e.g., four random words) for passwords you must memorize.
• Change passwords immediately if a service you use reports a data breach.