Password Strength Checker — How Entropy Works

Password strength is calculated based on the entropy of a string — the unpredictability of each character. Entropy is determined by two factors: character set size and length.

A 16-character lowercase passphrase (e.g., correcthorsebattery) has significantly more entropy than an 8-character mixed-case password (e.g., P@ss1234), because length multiplies the search space exponentially.

Best Practices

• Use a passphrase of 4+ random words for easy-to-remember high-entropy passwords
• Enable multi-factor authentication (MFA) on every critical account
• Store passwords in a password manager — never reuse across sites

FAQ

Is my password stored anywhere? Absolutely not. This tool uses only local JavaScript — no keystroke is ever sent over the network.