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Password Generator

Generate secure passwords and analyze password strength

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Password Generator Guide

A password generator creates random, unique passwords and passphrases so you avoid reuse and predictable patterns. It estimates entropy based on the selected character sets and length.

What is Password Generator?

The password generator lets you pick character sets (lowercase, uppercase, digits, symbols), enforce rules (no ambiguous characters, must include each set), and generate multi-word passphrases with spacing or separators.

How to Use the Password Generator

  1. Choose character sets: letters, digits, symbols; or select passphrase mode.
  2. Set length (e.g., 16-24 for passwords; 4-6 words for passphrases).
  3. Toggle options: avoid ambiguous chars, require all sets, exclude look-alikes.
  4. Generate and copy; store it in a password manager.
  5. Enable 2FA on the account for an extra layer of security.

Formulas & Methods

  • Entropy (bits): H = L * log2(N) where L is length and N is the character set size.
    Example: lowercase+uppercase+digits+symbols N ~ 26+26+10+32 ~ 94.
  • Passphrase entropy: H = words * log2(V) where V is vocabulary size (e.g., 7,776-word list gives ~12.9 bits/word).
  • Policy checks: ensure at least one character from each selected set if required.

Assumptions & limitations

  • Entropy describes randomness, not resistance to phishing or malware.
  • Avoid copying to insecure clipboards on shared devices.
  • Do not reuse passwords; a breach on one site exposes others.

Examples

Example A — 16-char mixed
L = 16, N = 94 → H ~ 16*log2(94) ~ 16*6.554 = 104.9 bits (very strong).

Example B — 5-word passphrase
words = 5, V = 7,776 → H ~ 5*12.9 = 64.5 bits (strong for many uses; go longer for critical accounts).

| Mode | Length | Est. Entropy | |---|---:|---:| | Mixed charset | 16 | ~105 bits | | Passphrase | 6 words | ~77 bits | | Mixed charset | 24 | ~157 bits |

Pro Tips & Best Practices

  • Prefer length and randomness over complexity rules like forced substitutions.
  • Use a reputable password manager and unique passwords per site.
  • Turn on 2FA (TOTP, hardware key) where available.
  • Beware of phishing—no password is safe if you give it away.
  • Regenerate passwords if they are ever exposed or reused.

Related Calculators

FAQ

Q: How strong is my password?

A: Strength depends on length, character set size, and randomness. Entropy roughly equals length times log2 of the character set size.

Q: What length should I use?

A: For accounts, 12-16 random characters is a common minimum; use longer (e.g., 20+) for critical accounts or passphrases.

Q: Are passphrases better?

A: Random multi-word passphrases can be strong if generated from a large word list and spaced or hyphenated.

Q: Should I reuse passwords?

A: No—use a unique password per site and a password manager to store them.

Q: What about 2FA?

A: Enable two-factor authentication for critical accounts in addition to strong passwords.

Engineering note: Passwords are generated locally in your browser; avoid saving sensitive credentials on shared devices.

Call to Action

Select your character sets and length, generate a unique password, and save it securely—then enable 2FA for key accounts.