Passphrase Generator
Free passphrase generator using the EFF wordlists. It picks random words or characters in your browser and shows the exact entropy of each result in bits.
Updated
One group of digits from 1 to 6 per word: five for the long list, four for the short lists.
Options
EFF long list: 7,776 words, 12.9 bits per word, five dice per word.
Select Generate to create a passphrase.
What Is a Passphrase Generator?
The passphrase generator picks words at random from the three EFF wordlists and shows the entropy of the result in bits, with the list size and word count behind the figure. Password mode draws random characters from the character sets you select. Dice rolls mode looks up the words for dice you roll yourself, so no website chooses your passphrase. Every random pick uses crypto.getRandomValues in your browser.
How to Use the Passphrase Generator
- Choose Passphrase, Password or Dice rolls.
- Set the number of words or the length. The wordlist, character sets, separator, and count are under Options.
- Read the result at the top of the panel. A new setting creates a new result, and Generate creates another with the same settings. Copying never changes it.
- In Dice rolls mode, type the numbers you rolled: five digits per word for the long list, four for the short lists.
- Copy the result into your password manager or wherever you need it.
How It Works
Each word comes from a published list. For k words picked at random from a list of n words there are n^k possible passphrases, and an attacker needs about n^k / 2 guesses on average to find one (EFF, 2016). Each added bit of entropy doubles the number of guesses.
The EFF long list has 7,776 words, which gives about 12.9 bits per word, and EFF recommends six words from it for about 77 bits. The two short lists have 1,296 words each and give about 10.3 bits per word, so eight short-list words give about 82 bits.
EFF built the long list from words of 3 to 9 characters, preferring the most recognized words and then the most concrete ones, and no word in it is a prefix of another. Short list 1 holds the 1,296 most memorable and distinct words. In short list 2 every word has a unique three-character prefix, and any two words are at least an edit distance of 3 apart.
The dice method comes from Arnold Reinhold's Diceware, first published in 1995, which picks words from a numbered list with ordinary dice. With the EFF long list you roll five dice per word and look up the word next to the number, so 43463 is panoramic. The short lists use four dice per word (EFF). Dice rolls mode only looks up the words, so the randomness comes from your dice.
Every random pick on this page uses crypto.getRandomValues. MDN describes its generator as suitable for cryptographic purposes, and the Web Cryptography specification calls for a cryptographically strong generator seeded with truly random values. The page does not use Math.random, which MDN says does not provide cryptographically secure random numbers. To keep every word and character equally likely, the page draws again whenever a random value falls at or above the largest multiple of the list size below 2^32. When every character set is required, it draws the whole password again until each set appears, and the entropy is the log2 of the exact number of such passwords, counted by inclusion and exclusion.
NIST SP 800-63B-4, final since July 2025, sets rules for services. A service must require at least 15 characters for a password used as the only factor and at least 8 for one used with multi-factor authentication, should permit at least 64 characters, and must not impose composition rules such as required character types. NIST calls password length a primary factor in password strength.
The wordlists are the EFF files, used unchanged. EFF publishes its original material under the Creative Commons Attribution 4.0 International license (EFF copyright policy).
Standards
Scope
What It Checks
- +Picks every word and character with crypto.getRandomValues and rejection sampling, so each one is equally likely.
- +Uses the three EFF wordlists, unchanged.
- +Shows the exact entropy of each result, including when every character set is required.
- +Looks up the words for your own dice rolls.
- +Creates a new result when you select Generate or pick settings you have not used yet. Copying, Reset, and switching back to earlier settings show the earlier result again.
What It Does Not Check
- -It does not send or store anything it generates, and it writes nothing to the page address.
- -It does not rate passwords you type. The entropy figure applies only to results this page generated.
- -It does not check passwords against breach lists.
Defensive Use
EFF names the passphrase of an encryption key, such as a PGP or SSH key, and the master password of a password manager as good uses for random passphrases. NIST SP 800-63B-4 lets a service assign passwords randomly, and it counts machine-generated random passwords among the mitigations that are more effective against modern brute-force attacks than extra password requirements.
Frequently Asked Questions
What is a Passphrase Generator?→
The passphrase generator picks words at random from the three EFF wordlists and shows the entropy of the result in bits, with the list size and word count behind the figure. Password mode draws random characters from the character sets you select. Dice rolls mode looks up the words for dice you roll yourself, so no website chooses your passphrase. Every random pick uses crypto.getRandomValues in your browser.
What is the Passphrase Generator used for?→
Creating the master password of a password manager, the passphrase of an encryption key, or a random password for an account, and checking how many bits a given number of words or characters gives.
Is my data sent anywhere?→
No. The Passphrase Generator runs in your browser. What you enter stays on this page and is not sent to ImmunitySec or anyone else.
How is the Passphrase Generator used defensively?→
EFF names the passphrase of an encryption key, such as a PGP or SSH key, and the master password of a password manager as good uses for random passphrases. NIST SP 800-63B-4 lets a service assign passwords randomly, and it counts machine-generated random passwords among the mitigations that are more effective against modern brute-force attacks than extra password requirements.
How many words should a passphrase have?→
EFF suggests six words from its long list for most uses, which gives about 77 bits. Eight words from one of its short lists give about 82 bits. Each extra word from the long list adds about 12.9 bits.
How long should a password be?→
NIST SP 800-63B-4 requires services to set a minimum of 15 characters for a password used as the only factor, and allows a minimum of 8 for a password used with multi-factor authentication. Services should permit at least 64 characters, which leaves room for passphrases.
Do I need symbols and numbers in a password?→
NIST SP 800-63B-4 says services shall not impose composition rules such as required mixtures of character types, and it calls password length a primary factor in password strength. The entropy figure on this page shows how much each character set adds.
Is it safe to generate a password on a website?→
This page generates in your browser with crypto.getRandomValues, which MDN describes as suitable for cryptographic purposes, and nothing leaves the page. MDN also notes that the Web Cryptography specification sets no minimum degree of entropy. If you prefer not to rely on any website, roll physical dice and use Dice rolls mode, which only looks up the words.
What is a passphrase?→
A passphrase is a password made of several words. NCSC advises combining three random words, and EFF's method picks each word from a numbered list with dice. EFF says randomly generated passphrases offer a major security upgrade over user-chosen passwords.
Can I use one passphrase for several accounts?→
EFF says a passphrase should be used for a single purpose only, and especially not for more than one online account. NIST SP 800-63B-4 requires services to allow password managers and autofill, which makes a different random password for each account practical.
Wordlists: EFF long wordlist, short wordlist 1 and short wordlist 2 by the Electronic Frontier Foundation, used unchanged under the Creative Commons Attribution 4.0 International license.