What Makes a Password Strong?
A strong password combines length, character variety, unpredictability, and uniqueness. The National Institute of Standards and Technology (NIST) currently recommends prioritizing password length above all else — a 16-character passphrase using random words is more secure than a complex 8-character password. Character variety (uppercase, lowercase, numbers, special characters) multiplies the search space attackers must cover.
Understanding Password Entropy
Password entropy measures unpredictability in bits. A password with 40 bits of entropy could be cracked by a powerful computer in hours. 60 bits would take years. 80+ bits provides practically unbreakable security against current hardware. Entropy is calculated from the character set size and password length: entropy = log2(charset_size ^ length). Adding one character can double or triple entropy.
Common Password Mistakes
Avoid using dictionary words, names, dates, or keyboard patterns (qwerty, 12345). Don't substitute obvious characters (@ for a, 3 for e, 0 for o) — hackers' dictionaries include these. Avoid using the same password across multiple sites — credential stuffing attacks reuse breached passwords. Never use passwords that include your username, email, or personal information.
Password Manager Recommendation
The best password is one you never have to remember. Password managers (Bitwarden, 1Password, KeePass) generate and store complex unique passwords for every site. They also alert you to breached passwords and autofill credentials securely. Our checker is a learning tool — in practice, let a password manager generate your passwords.
Two-Factor Authentication
Even the strongest password can be compromised if a service is breached. Always enable two-factor authentication (2FA) where available. An authenticator app (Google Authenticator, Authy) is far more secure than SMS-based 2FA.