Diceware Passphrase Generator

Cryptographically random passphrases made of short English words. Pick a count, set the casing and extras, get a strong passphrase you can actually memorise. Live in your browser, nothing uploaded.

3–10 · 6 = 62 bits
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How does Diceware work?

Diceware generates passphrases by drawing words at random from a fixed word list. With 1,296 short English words in the EFF list, each word contributes log2(1296) ≈ 10.34 bits of entropy. Six random words therefore give ≈ 62 bits — far stronger than any human-chosen password and easier to type.

Randomness comes from crypto.getRandomValues() with rejection sampling so the distribution over the word list is exactly uniform. The Diceware technique was published by Arnold Reinhold in 1995; the EFF short list we use is the canonical 2016 EFF word list (public domain).

Strength tiers (rough guidance): < 28 bits = very weak; < 36 = weak; < 60 = fair; < 80 = strong; < 128 = very strong; ≥ 128 = excellent.

One quirk: the EFF short list contains a single 4-character word with a hyphen, yo-yo. If you pick a hyphen separator you may occasionally see a doubled hyphen where this word lands at a boundary — just regenerate if it bothers you.

About this tool

Diceware generates passphrases from a wordlist using the browser's CSPRNG, the same method the EFF recommends in its diceware guide. By default, the tool uses the standard EFF long wordlist (7,776 words, ~12.9 bits per word). A 5-word passphrase gives ~64 bits of entropy, a 6-word passphrase ~77 bits, a 7-word passphrase ~90 bits. The words are joined with a separator of your choice (space, hyphen, underscore, or none) and the page reports the entropy in bits next to the passphrase.

When to use it

  • Generating a master password for a password manager that you will need to type occasionally — passphrases are easier to remember than random strings
  • Producing a memorable but high-entropy passphrase for a recovery key or a shared secret
  • Creating a passphrase for a KeePass or Bitwarden vault you want to be able to retype if your password manager is unavailable

When not to use it

  • You need a password you can paste from a manager without typing it — a random character string from the password generator is faster to copy
  • You need a passphrase in a specific language — the EFF wordlist is English. Other diceware wordlists exist in other languages; this tool uses EFF's English list
  • You need a passphrase shorter than 4 words — the entropy is below 50 bits, which is too low for any modern threat model

Frequently asked questions

Why does each word add about 12.9 bits?

The EFF long wordlist has 7,776 words, and log2(7776) is approximately 12.925. Each word chosen at random from that list contributes that many bits of entropy. Five words give ~64 bits, six give ~77, seven give ~90.

Is the word selection truly random?

Yes. The tool uses crypto.getRandomValues to select each word index, which is the browser's CSPRNG. The randomness is not predictable from outside the browser tab.

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