Passphrase generator
Random words from the EFF diceware list, drawn in your browser. Easy to type, easy to remember, and the strength maths is shown in full.
The generator needs JavaScript: every word is picked on your device, never on a server.
Why random words beat "P@ssw0rd!"
A passphrase is a password made of several words. What makes one strong is not the words themselves but how they were chosen. If a machine picks each word uniformly at random from a list of 7,776, every word adds log2(7,776) ≈ 12.9 bits of entropy. Six words give 6 × 12.925 = 77.5 bits, or about 2.2 × 1023 equally likely passphrases. That holds even if the attacker has the exact same wordlist and knows you used this tool.
Compare the usual advice: take a word, capitalise the first letter, swap an a for @, add a 1! at the end. Cracking tools try exactly those substitutions first. You get something hard to remember that is still easy to guess.
How this generator works
- It loads the EFF wordlist you pick (bundled with the page, no network call).
- For each word it asks
crypto.getRandomValues for a 32-bit number and throws away values that would bias the result (rejection sampling), so every word is exactly equally likely. - It joins the words with your separator and applies your capitalisation. Random options (random capitals, random digits) are counted in the entropy; fixed styles are not, because they're predictable.
The small number under each tag is that word's dice code. Roll the same five numbers with real dice and you'd land on the same word in the EFF list. See the diceware dice roller to do it by hand.
Feel how one extra word changes things
Good places for a passphrase
- Password-manager master password. The one you type often and can't store anywhere else. Six or seven words.
- Computer login and full-disk encryption (BitLocker, FileVault, LUKS). Offline attacks are possible, so aim for 77+ bits.
- Your main email account, since it can reset everything else.
- Wi-Fi, which guests have to type from a card. See the Wi-Fi password generator.
For the other hundred accounts, let your password manager generate long random strings you never type. Where a site demands capitals, numbers and symbols, the memorable password generator dresses a passphrase up to pass the check.
How to remember it
Make a silly mental picture that links the words in order, and say it out loud. Then type it a dozen times over the next couple of days. Write it on paper and keep that somewhere safe until you know it by heart. Don't reorder or swap words for ones you like better: your own choices are exactly what attackers model.
A passphrase earns its keep by being impossible to predict. For the opposite pleasure, something perfectly predictable and well explained, try ahaboo's narrated explainer on why the Moon has phases.
Passphrase questions
Is this passphrase generator safe to use for a master password?
Yes. Words are chosen in your browser using crypto.getRandomValues, the same cryptographically secure random source browsers use for encryption keys. No passphrase is sent over the network, logged or stored unless you switch on local history. You can load the page, turn off Wi-Fi and it keeps working.
How many words should my passphrase have?
Six words from the EFF long list (about 77.5 bits) is a strong default for a password-manager master password or anything you cannot protect with a second factor. Five words (about 64.6 bits) is reasonable for ordinary accounts that rate-limit logins. Use seven or more if you want a margin that will last for decades.
Do capitals, numbers and symbols make it much stronger?
Barely. One random digit adds 3.3 bits and one symbol from our set of 10 adds 3.3 bits; one extra word adds 12.9. Add them only when a site insists, and let the word count carry the strength.
Where do the words come from?
From the Electronic Frontier Foundation's diceware wordlists (2016), published under CC BY 3.0 US. The long list has 7,776 words chosen to be concrete, memorable and free of offensive or easily confused terms. Both short lists have 1,296 words.
Why is the strength shown in bits?
Bits count equally likely possibilities: n bits means 2 to the power n combinations. Because every word is an independent, uniform pick from a known list, the maths is exact: words × log2(list size). We assume the attacker knows the list and your settings, so the figure is honest, not flattering.
Can I check a passphrase I already made up myself?
Use the entropy calculator page: it can tell you how many of your words are on the EFF lists, all in your browser. A phrase you picked yourself is usually weaker than its length suggests, because people choose predictable word combinations. For a breach lookup, use a dedicated checker.