Password Generator
Generate a strong random password or a memorable passphrase, with its entropy shown — reproducible from a seed, so you can regenerate the same one.
Characters are drawn from the set you choose using a seeded generator, so the same seed always produces the same password and a new seed produces a new one.
How the password generator works
Characters are drawn from the set you choose using a seeded generator, so the same seed always produces the same password and a new seed produces a new one. Passphrase mode picks words from a list in the style of Diceware, which gives high entropy in a form people can actually remember and type. The entropy shown assumes random selection, which is exactly what happens here — the weakness of human-chosen passwords does not apply.
Treat a password generated on any web page as good rather than perfect. The generator here is seeded and reproducible by design, which is useful for regenerating a password you lost before saving but is the opposite of what you want for a high-value secret. For anything critical, use a password manager's own generator: it draws on your operating system's cryptographic random source and stores the result where you need it.
Formula: entropy = length × log₂(character set size)
Worked examples
| Inputs | Generated | Note |
|---|---|---|
| 16 random characters | z8gGl5HzOXv7W1b8 | 95 bits — very strong |
| A five-word passphrase | scarlet-otter-apple-mustard-summit | memorable and strong |
| 24 characters with symbols | fgYL8l9+&ekcGZtwe#Ok9Eqp | for a password manager entry |
FAQFrequently asked questions
Is it safe to generate a password on a web page?
Treat it as good rather than perfect. This generator is deliberately seeded, so the same seed reproduces the same password — handy for regenerating one you lost, but the wrong property for a high-value secret. For critical accounts use a password manager's generator, which draws on your operating system's cryptographic random source.
Why does it use a seed?
So you can regenerate the same password if you lose it before saving, and so the result is predictable for testing. Change the seed for a fresh password — and do not reuse a seed you have shared.
Should I use a passphrase or random characters?
Random characters if a password manager will remember it; a passphrase if you have to type or remember it yourself, such as a device login or the manager's own master password.
How long should a password be?
Sixteen random characters, or five random words, is comfortably beyond brute force. Longer costs nothing when software remembers it for you.
Do I still need different passwords per site?
Yes — the main real-world risk is reuse. One breach then unlocks every account sharing that password.
Where these figures come from
- IEC 80000-13 — Information science and technology (quantities and units) — the decimal (kB, MB) versus binary (KiB, MiB) prefixes used throughout
- RFC 4632 — Classless Inter-domain Routing (CIDR) — the address-plan arithmetic behind the subnet calculator
- RFC 1918 — Address Allocation for Private Internets — the private ranges the subnet calculator recognises
- NIST SP 800-63B — Digital Identity Guidelines, Authentication — length over composition rules; the basis of the password guidance here
- NIST SP 800-57 Part 1 — Recommendation for Key Management — key-strength comparisons used by the key-space calculator
- NIST — Digital Identity Guidelines (SP 800-63) — US federal authentication standard
Last checked: September 2026. Units follow the SI decimal convention (IEC 80000-13 defines the binary alternatives); network and security figures cite the defining standard.