What this tool does
The Diceware Passphrase Generator builds passphrases the way the original Diceware method intended — by picking words at random from a large, carefully curated list — except the “dice” here are your browser’s cryptographically secure random number generator instead of physical six-sided dice. Pick a word count from 3 to 12, choose how the words should be joined, and generate as many passphrases as you want.
How the entropy works
Each word is drawn from the EFF Large Wordlist, which has exactly 7,776 entries (6⁵, matching five dice rolls). Because log₂(7,776) ≈ 12.925, every word you add contributes about 12.9 bits of entropy:
| Words | Entropy | Roughly as strong as |
|---|---|---|
| 4 | ~51.7 bits | A short random password |
| 6 | ~77.5 bits | A solid, long-lived account password |
| 8 | ~103.4 bits | A password-manager master password |
The tool also offers an optional trailing random digit (adds log₂(10) ≈ 3.3 bits) and a capitalize toggle, for sites that insist on mixed case or a digit even though word-based entropy already makes that unnecessary for security.
No modulo bias
A naive way to pick a random word is randomInt() % 7776, but that subtly favors the first few hundred words in the list whenever the random generator’s range isn’t an exact multiple of 7,776. This tool uses rejection sampling instead: any draw that would introduce that bias is discarded and re-rolled, so every one of the 7,776 words is exactly equally likely.
Privacy
Word selection, joining, and display all happen in your browser using the Web Crypto API. Nothing about your passphrase — or even the fact that you generated one — is sent to any server.