How many words should my passphrase have?

Five words from the EFF large wordlist gives about 64 bits of entropy, enough for most accounts. Use six words (77 bits) for anything critical like a password manager master password or disk encryption.

Are word passphrases really as strong as random characters?

Yes, when the words are chosen randomly from a large list. Strength comes from the number of equally likely possibilities, and 7,776 possible words per slot compounds fast. correct-horse-battery-staple beats Tr0ub4dor&3, exactly as the famous xkcd argued.

Which wordlist does this use?

The EFF large wordlist: 7,776 common, distinct, easy-to-spell English words designed for diceware. Each word adds 12.9 bits of entropy.

Passphrase Generator

Random words you can actually remember, with entropy you can actually trust. Diceware from the EFF large wordlist.

Runs entirely in your browser. Nothing you type or generate is ever sent to a server.

Words: 5 Separator Capitalize words Add a digit

Why passphrases work

A passphrase gets its strength from randomness, not obscurity. Each word here is drawn uniformly from the EFF large wordlist of 7,776 words, so every word contributes log2(7776) = 12.9 bits of entropy: four words is 51.6 bits, five words 64.6, six words 77.5. An attacker who knows exactly which wordlist and how many words you used still has to search the whole space.

The word list is the EFF Large Wordlist, created by the Electronic Frontier Foundation and used here unmodified under the Creative Commons Attribution 3.0 United States licence.

That is the crucial point people miss: the strength calculation assumes the attacker knows your method. Never pick the words yourself; human-chosen words cluster hard around a few thousand favorites and famous phrases.

When to prefer a passphrase

Master passwords for password managers, the one secret you must remember.
Device logins and disk encryption, typed daily on a keyboard.
Wi-Fi keys read aloud to guests, where random characters cause pain.

Want examples with the math shown? See passphrase examples, or test any result in the strength checker.

Frequently asked questions

How many words should my passphrase have?: Five words from the EFF large wordlist gives about 64 bits of entropy, enough for most accounts. Use six words (77 bits) for anything critical like a password manager master password or disk encryption.
Are word passphrases really as strong as random characters?: Yes, when the words are chosen randomly from a large list. Strength comes from the number of equally likely possibilities, and 7,776 possible words per slot compounds fast. correct-horse-battery-staple beats Tr0ub4dor&3, exactly as the famous xkcd argued.
Which wordlist does this use?: The EFF large wordlist: 7,776 common, distinct, easy-to-spell English words designed for diceware. Each word adds 12.9 bits of entropy.