Password Strength Checker

A strong password combines length (12+ characters), character variety (uppercase, lowercase, digits, and symbols), and avoids common words, sequential patterns like "123" or "abc", and repeated characters. Length is the single most important factor — a random 16-character password is exponentially harder to crack than an 8-character one, even with symbols.

Password entropy, measured in bits, quantifies the unpredictability of a password. It is calculated as log2(charset_size) × length. Higher entropy means more possible combinations, making brute-force attacks harder. A password with 60+ bits of entropy is generally considered strong; 80+ bits is very strong for most threat models.

The main attack types are: (1) Brute force — trying every possible combination; (2) Dictionary attacks — using lists of common words and passwords; (3) Credential stuffing — replaying leaked username/password pairs from data breaches; (4) Rainbow table attacks — using precomputed hash lookups. Using unique, random, long passwords defeats all of these.

Yes. Password managers (1Password, Bitwarden, Dashlane, etc.) generate and store long, unique, random passwords for every site, so you only need to remember one strong master password. This eliminates password reuse — the single biggest real-world security risk — and makes it practical to use 20+ character passwords everywhere.

2FA adds a critical second layer of security, but it does not make your password unimportant. A weak password combined with SMS 2FA can still be compromised via SIM-swapping or phishing. Best practice is to use both a strong, unique password and a strong 2FA method (TOTP app or hardware key like YubiKey) together.