Generate strong, random passwords with custom length, character sets, and rules. Measure password strength and entropy instantly — no data sent to any server.
Secure Password Generator
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How Secure Is Your Password? Entropy Explained
Password strength is measured in bits of entropy — the amount of uncertainty an attacker faces trying to guess it. Every bit of entropy doubles the number of possible passwords. A 128-bit entropy password would take longer than the age of the universe to crack even with the fastest hardware.
Entropy by Password Type
8 chars, all lowercase: ~37.6 bits — crackable in hours on modern hardware
12 chars, mixed case + numbers: ~71.5 bits — would take years
16 chars, all character types: ~104 bits — practically uncrackable by brute force
Passphrase (4 random words): ~51 bits — less entropy but easier to remember
Password Generator Privacy
This tool uses the browser's crypto.getRandomValues() API — a cryptographically secure random number generator that never sends anything to a server. Generated passwords are only visible on your screen and in your clipboard. No logs, no history, no server-side processing.
Password Best Practices
Use a unique password for every account — password reuse is the #1 cause of account takeovers
Store passwords in a password manager (Bitwarden, 1Password, Dashlane) — never in a spreadsheet
Enable 2FA/MFA on all important accounts — even a leaked password won't gain access
16+ characters is the practical minimum for new accounts in 2024
Frequently Asked Questions
Minimum 16 characters for important accounts (banking, email, password manager master password). 12 characters is the absolute minimum for anything. Length contributes more to entropy than complexity — a 20-character lowercase password is stronger than an 8-character password with symbols. NIST guidelines (2024) recommend 15+ characters and prioritize length over complexity requirements.
Yes, if the tool uses crypto.getRandomValues() (as this tool does) — it's the same cryptographic RNG your OS uses. The passwords are generated locally in your JavaScript environment and never transmitted anywhere. However, be cautious about online password generators that might log generated passwords server-side. Always use a well-known, open-source tool or generate offline.
Entropy — the number of possible combinations an attacker must search through. Entropy = log₂(charset_size^length). More characters and larger character set = higher entropy = stronger password. The character set size: lowercase only = 26, lower+upper = 52, lower+upper+digits = 62, + symbols = ~94. A 16-char password with all character types has ~104 bits entropy.
Passphrases (4–6 random words like 'correct-horse-battery-staple') are easier to memorize while being reasonably secure. 4 random words from a 2,000-word list = ~44 bits entropy. 6 words = ~66 bits. A 16-char random password with mixed characters = ~104 bits. For things you must type regularly (OS login), a passphrase wins; for password-manager-stored accounts, use maximum-entropy random passwords.