Generate a Diceware Passphrase Online Free
🎲 Build a Memorable, High-Entropy Passphrase
Pick your word count and style — the exact entropy and estimated crack time update live. Nothing leaves your device.
🔢 Word Count
6 words (~77.5 bits) is a strong default. Use 7-8 for highly sensitive accounts or encryption keys.
✨ Style
🎯 Manual Dice Lookup (Trust No RNG)
Roll five physical 6-sided dice and type the digits (1-6 each) to look up that exact word from the offline-verifiable EFF list — no randomness is generated by this tool for this lookup.
Quick answer: Pick a word count (6 is a strong default), a separator, and a capitalization style, then click Generate. Each word is picked using crypto.getRandomValues from the official EFF 7,776-word Diceware list, giving an exact, calculable entropy (~12.9 bits per word) shown live alongside an estimated crack time at several attack speeds. Prefer to trust dice over any RNG, including this one? Use the manual lookup to convert your own physical dice rolls into words. Nothing you generate is ever uploaded or stored.
- Cost: Free, unlimited passphrases, no signup.
- Where it runs: 100% in your browser — no upload, no server.
- Word list: Official EFF Large Wordlist (7,776 words), bundled locally.
- Randomness:
crypto.getRandomValueswith rejection sampling — no modulo bias. - Entropy shown: Exact bits for your chosen configuration, plus a crack-time estimate.
- Trust-no-RNG mode: Manually look up words from your own physical dice rolls.
🎲 Real Diceware, Not a Gimmick: This uses the actual, unmodified EFF Large Wordlist and unbiased random selection — the same standard behind command-line Diceware tools.
🔢 Entropy Is Approximate for Extras: The core word entropy is exact; entropy added by an optional number or symbol is an approximate lower-bound estimate.
✅ Privacy: Every passphrase is generated locally in your browser. Nothing is transmitted, logged, or stored.
✅ 100% Private: Passphrases are generated locally using JavaScript and the bundled word list. No data is ever uploaded to a server or stored anywhere.
Note: Nothing you generate here is saved — reloading the page clears it completely.
How to Generate a Diceware Passphrase
Choose Word Count
Pick how many words your passphrase should contain — 6 is a strong default.
Set Separator & Style
Choose a separator and whether to capitalize each word.
Generate
Click Generate to get a new random passphrase and see its exact entropy.
Copy & Save
Copy the passphrase and store it in a password manager.
🔒 Every Word Is Chosen on Your Device
This tool uses crypto.getRandomValues with rejection sampling over the 7,776-word list, so every word has an exactly equal chance of being chosen — computed entirely in your browser tab, with nothing ever transmitted anywhere.
Common Uses for a Passphrase / Diceware Generator
Master Passwords
Create a passphrase you can actually type from memory for your password manager's master password.
Disk & Backup Encryption
Generate a high-entropy passphrase for full-disk encryption or encrypted backup archives.
Wi-Fi & Router Passwords
Set a Wi-Fi password that guests can actually read and type correctly off a card.
Shared Family Accounts
Create a passphrase multiple people need to remember and type without a manager.
Server & API Secrets
Generate a memorable-enough root or admin passphrase for a system that's typed occasionally, not stored in a vault.
Teaching Entropy & Security
Demonstrate exactly how word count and list size translate into real, calculable entropy.
Why Use This Passphrase / Diceware Generator?
- Real Diceware: Uses the unmodified, official EFF 7,776-word list.
- Unbiased Randomness: Rejection sampling over Web Crypto avoids modulo bias entirely.
- Exact Entropy: Real bits-of-entropy math shown live, not a vague strength label.
- Crack-Time Estimates: See how your passphrase holds up against multiple attack speeds.
- Trust-No-RNG Mode: Manually convert your own physical dice rolls into words instead.
- Fully Customizable: Word count, separator, capitalization, optional number/symbol.
- Nothing Saved: No local storage, no cookies — closing the tab clears everything.
- 100% Free & Private: No account, no tracking, no server involved.
Passphrase / Diceware Generator – Complete Guide
A password like Tr0ub4dor&3 is hard to remember and only moderately hard to guess. A passphrase like correct-horse-battery-staple is easy to remember and, with enough words from a large enough list, far harder to guess - this is the insight behind Diceware, and the joke behind the famous xkcd comic that popularized it.
What Is Diceware, Really?
Diceware, invented by cryptographer Arnold Reinhold, assigns every word in a fixed list a unique 5-digit number where each digit is 1-6 - exactly what five rolls of a six-sided die can produce (65 = 7,776 possible outcomes). Roll five dice, look up the resulting number in the list, and you get one word with a mathematically exact ~12.925 bits of entropy. Chain several such words together and the entropy simply adds up - six words give roughly 6 × 12.925 ≈ 77.5 bits.
How This Generator Actually Works
Selecting a word fairly from 7,776 options isn't as simple as randomByte % 7776, since 7,776 doesn't evenly divide 256 or any power of two - a naive modulo would make some words very slightly more likely than others. Instead, this tool draws random 16-bit values from crypto.getRandomValues and uses rejection sampling: any draw of 7,776 or greater is simply discarded and re-rolled, so every remaining word has an exactly equal 1-in-7,776 chance. The chosen words are then joined with your selected separator and capitalization, and the total entropy is computed as words × log2(7776), plus an approximate addition if you opted to insert a random number or symbol.
Diceware Passphrase vs Random Character Password vs PIN
| Aspect | Diceware Passphrase (this tool) | Random Character Password | 4-Digit PIN |
|---|---|---|---|
| Entropy (typical) | ~77.5 bits (6 words) | ~72 bits (12 mixed chars) | ~13.3 bits |
| Easy to type from memory? | Yes | Difficult | Yes |
| Best used for | Master passwords, disk encryption | Stored passwords in a manager | Device unlock, low-value gates |
How Many Words Do You Actually Need?
| Word Count | Entropy | Recommended For |
|---|---|---|
| 4 words | ~51.7 bits | Low-value, rate-limited accounts only |
| 5 words | ~64.6 bits | Reasonable minimum for most accounts |
| 6 words | ~77.5 bits | Strong default - password managers, email |
| 7-8 words | ~90-103 bits | Encryption keys, highly sensitive accounts |
Security and Privacy Considerations
- No Data Upload: Every generated passphrase stays on your device.
- No Server Processing: Word selection runs entirely as client-side JavaScript.
- No Storage: Nothing is written to local storage, cookies, or a server.
- Unbiased Selection: Rejection sampling guarantees every word has an equal probability.
Browser Compatibility and Technical Requirements
This Passphrase Generator works in modern browsers that support:
- Web Crypto API (
crypto.getRandomValues): For cryptographically secure random word selection. - Clipboard API: For one-click copying of the generated passphrase.
Supported Browsers:
- ✅ Chrome/Edge 11+
- ✅ Firefox 21+
- ✅ Safari 6.1+
- ✅ Mobile Chrome (Android), Mobile Safari (iOS)
Troubleshooting Common Issues
Explanation: The official EFF Large Wordlist is a general-purpose English word list and wasn't filtered for tone. Solution: Simply click Generate again - there's no penalty to regenerating until you get a combination you're happy to use.
Explanation: Some legacy password policies require a mix of character types regardless of overall length or entropy. Solution: Toggle on "Add a random number" or "Add a random symbol" before generating.
Explanation: Only digits 1 through 6 are valid for each of the five positions, matching a real six-sided die. Solution: Re-check your rolls - a 0, 7, 8, or 9 in any position isn't a valid Diceware roll.
Explanation: This page is a visual generator, not a downloadable list. Solution: The official EFF Large Wordlist is published directly by the Electronic Frontier Foundation and widely mirrored - search for "EFF Large Wordlist" to find the canonical source file.
Frequently Asked Technical Questions
Question 1: How exactly is the entropy calculated?
Answer: Each word contributes log2(7776) ≈ 12.925 bits, since any of 7,776 equally likely words could have been chosen. Total word entropy is simply that value multiplied by your chosen word count.
Question 2: Why not just use Math.random()?
Answer: Math.random() is not specified to be cryptographically secure and can be predictable in some engines. This tool uses crypto.getRandomValues(), the Web Crypto API's cryptographically secure random number source, instead.
Question 3: What is rejection sampling and why does it matter here?
Answer: Since 7,776 doesn't evenly divide a power of two, taking a random 16-bit number modulo 7,776 would make roughly the first 512 words in the list very slightly more likely than the rest. Rejection sampling discards any draw of 7,776 or higher and tries again, eliminating that bias completely.
Question 4: How is the crack-time estimate calculated?
Answer: The total number of possible passphrases (2 raised to the entropy in bits) is divided by an assumed guesses-per-second rate for a given attack scenario, then halved for an average-case guess - the same standard approach used by most password strength estimators.
Question 5: Does this tool need an account, server, or API key?
Answer: No. The word list is bundled directly into the page and all computation happens with JavaScript already loaded here — no account, backend, or API key is ever required.
Glossary of Terms
- Diceware
- A method for generating passphrases by using physical dice rolls to randomly select words from a fixed 7,776-word list.
- Passphrase
- A password composed of multiple random words rather than a single string of arbitrary characters, designed to be both high-entropy and easy to remember.
- Entropy
- A measure, in bits, of how unpredictable a password or passphrase is; each doubling of the number of possible outcomes adds one bit.
- EFF Large Wordlist
- A 7,776-word list published by the Electronic Frontier Foundation, specifically curated for use with the Diceware passphrase method.
- Brute-Force Attack
- An attack that systematically tries every possible password or passphrase combination until the correct one is found.
Frequently Asked Questions
Yes, completely free with no signup and no limit on how many passphrases you generate.
No. Every word is selected locally using the browser's Web Crypto API and the bundled word list. Nothing is transmitted over the network or stored.
Diceware is a method, invented by Arnold Reinhold, for creating passphrases by rolling physical dice to randomly select words from a fixed 7,776-word list, so the resulting passphrase is both highly random and easy to remember.
Six words from this word list gives roughly 77.5 bits of entropy, which is considered strong for most accounts; five words (about 64.6 bits) is a reasonable minimum, and seven or more is recommended for highly sensitive accounts or encryption keys.
For the same length of typing effort, a multi-word passphrase from a large wordlist is typically far easier to remember and type than a random character string of comparable entropy, while offering similar or greater resistance to guessing.
That's the official Diceware index for that word (each digit 1-6, as if rolled on a physical die) from the EFF's published wordlist, so you can verify the word against a printed copy of the same list if you don't want to trust any random number generator, including this one.
This tool uses the EFF Large Wordlist, a 7,776-word list published by the Electronic Frontier Foundation under a Creative Commons Attribution license, specifically designed for generating secure Diceware passphrases.
It isn't necessary for security if you use enough words, but some services require a digit or symbol - this tool can optionally insert one, and the entropy display updates to reflect it.
Final Thoughts
A good passphrase should be something you can actually type from memory without a manager open next to you, while still standing up to serious guessing attempts. Six or more words from a real, unmodified Diceware list - picked with unbiased, cryptographically secure randomness - gets you both. Set your word count above and generate your first passphrase.
Choose your word count above and generate your first passphrase!