What is a passphrase?
A passphrase is a password made of several randomly chosen words, such as gravy-unfold-stilt-pelican-reopen-nifty. Because each word comes from a list of 7,776, every word adds about 12.9 bits of entropy — the same as two random characters with symbols, but far easier for a human to picture, remember and type.
The idea is called Diceware: originally you rolled five dice to pick each word from a numbered list. This generator does exactly the same with crypto.getRandomValues() instead of dice, using the EFF long wordlist, which was designed to contain only distinct, familiar, easy-to-spell words with no offensive terms.
How many words do you need?
| Words | Entropy | Recommended for |
|---|---|---|
| 4 | 52 bits | Accounts protected by rate limiting and 2FA |
| 5 | 65 bits | Device logins, Wi-Fi |
| 6 | 78 bits | Password-manager master password, disk encryption |
| 7 | 90 bits | Long-term secrets, crypto wallets, PGP keys |
| 8+ | 103+ bits | Maximum security, offline attack resistance for decades |
These numbers hold even if the attacker knows you used this exact wordlist. Security comes from the random choice, not from the list being secret.
Why passphrases beat “complex” passwords
The famous comparison is “correct horse battery staple” versus “Tr0ub4dor&3”: the second looks complicated but follows a guessable pattern (a word with common substitutions), while four truly random words are both stronger and easier to recall. Modern guidance from NIST agrees — length and randomness matter, composition rules don’t.
Options explained
- Separator. Hyphens are the most readable and widely accepted. Random digit places a different random number between words, adding 3.3 bits per gap.
- Capitalize. Helps with sites that demand an uppercase letter. It does not add entropy because it is applied to every word.
- Add a number / symbol. Satisfies old composition rules. The number adds 6.6 bits, the symbol 3 bits.
Tips for remembering your passphrase
- Picture a silly scene linking the words in order — the stranger, the better.
- Type it a few times a day for the first week.
- Never “improve” it by swapping in your own words; that destroys the randomness.
- Write it down and keep it in a safe place until it is memorised.
Wordlist: EFF Large Wordlist by the Electronic Frontier Foundation, licensed CC BY 3.0 US.
Last updated: · Reviewed by the Password Generator team