Strong Password Generator: How to Create Uncrackable Passwords
What Makes a Password Strong?
A strong password is one that's difficult to guess or crack by brute force. The two main factors are length and randomness. A long, truly random password is vastly harder to crack than a short complex one — even if the short one uses special characters.
Weak passwords share common patterns: dictionary words, predictable substitutions (@ for a, 3 for e), keyboard walks (qwerty, 123456), and personal information (birthdays, names, addresses). Password crackers are trained on all of these patterns and will try them first.
Password Entropy Explained
Password strength is measured in bits of entropy — how many guesses an attacker needs to try all possible passwords of that type. Entropy = log2(character_set_sizepassword_length).
- 8-char lowercase only: ~38 bits — crackable in seconds with a GPU
- 8-char mixed case + numbers: ~48 bits — crackable in hours
- 12-char mixed case + numbers + symbols: ~79 bits — years with current hardware
- 16-char mixed case + numbers + symbols: ~105 bits — effectively uncrackable
- 5-word passphrase (from a 2048-word list): ~55 bits — very hard to crack, easy to remember
Recommendation: Generate passwords of at least 16 characters using all character types. For accounts you need to type manually, use a 4–6 word passphrase instead.
How to Use the Generator
Choose a length of 16 characters or more for strong passwords. 12 is the practical minimum; 20+ for critical accounts like email and banking.
Include uppercase letters, lowercase letters, numbers, and symbols for maximum entropy. Remove symbols only if the target system doesn't support them.
Generate multiple passwords at once to pick one you prefer, or generate a batch for bulk account creation.
Never store passwords in a text file or spreadsheet. Copy directly into your password manager — 1Password, Bitwarden, LastPass, or your browser's built-in password manager.
Length vs Complexity
Length beats complexity. A 20-character lowercase-only password (2620 = ~94 bits) is stronger than a 10-character password with all character types (9510 = ~66 bits). The common requirement for "at least one uppercase, one number, one symbol" adds relatively little entropy compared to simply making the password longer.
This is why many modern security frameworks (NIST SP 800-63B) now recommend minimum length over complexity requirements — and why passphrases have become popular.
Passphrases as an Alternative
A passphrase is a sequence of random words — like "correct horse battery staple" (from the famous XKCD comic). Passphrases are:
- Easier to type and remember than random character strings
- Strong enough for most accounts when 4–6 words are chosen randomly
- Resistant to dictionary attacks if words are chosen randomly (not a phrase you'd say)
The key word is random — "ilovemydog" is terrible; "purple-staple-galaxy-fence" chosen by a random generator is much stronger.
Password Management Best Practices
- Use a password manager — 1Password, Bitwarden (open source and free), Dashlane, or your browser's built-in manager. Never reuse passwords across sites.
- Enable two-factor authentication (2FA) — a strong password + 2FA (especially an authenticator app, not SMS) makes accounts extremely resistant to compromise.
- Never reuse passwords — a breach at one site exposes all accounts using the same password (credential stuffing attacks).
- Change passwords after a breach — check haveibeenpwned.com to see if your email has appeared in known data breaches.