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Passphrase Generator

Generate a memorable word-based passphrase with the browser's secure generator — easier to remember than random characters, with an honest note on its strength.

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Quick Answer

Build a passphrase like tiger-harbor-velvet-ocean42 from randomly chosen words, using your browser's cryptographically secure generator. Choose 3–10 words and a separator, and a number from 0 to 99 is added on the end. It is far easier to remember than random characters — but be aware the built-in list holds only 29 words, so each word adds about 4.9 bits, well below a full Diceware list.

What the Passphrase Generator Does

Choose how many words (3 to 10, default 4) and a separator — hyphen, dot, underscore or space — and the tool strings together random words and tacks on a 0–99 number. Click to copy, or Generate for another.

Passphrases swap per-character density for memorability: four real words lodge in your memory where sixteen random symbols won't. The honest trade-off is the size of the word list, which we don't hide.

How It Works

For each word, the tool draws a random index from the Web Crypto generator and picks from a built-in list of 29 words, then joins the words with your separator and appends a random number from 0 to 99.

The selection is genuinely random — the same secure generator used for keys — so the strength comes from the draw, not from any cleverness in the words. The limit is simply how many words there are to draw from.

Generation algorithm

Words are chosen with crypto.getRandomValues, the browser's cryptographically secure generator, so the selection is truly random. The list itself is deliberately small and memorable: 29 built-in words.

  1. Step 1. For each of the N words, draw a random index from the Web Crypto generator.
  2. Step 2. Pick that word from the built-in 29-word list.
  3. Step 3. Join the chosen words with your selected separator.
  4. Step 4. Append a random number from 0 to 99.
  5. Step 5. Show the passphrase; click to copy, or Generate for a new one.

Passphrase entropy

bits ≈ (words × log2(list size)) + log2(100) (list size = 29 here, plus the 0–99 number)
Worked examples
4 words + number, 29-word list: 4 × log2(29) + log2(100) ≈ 26 bits
A 6-word EFF Diceware phrase (7,776 words): 6 × 12.9 ≈ 77 bits

The whole difference is the list size. EFF's Diceware list has 7,776 words at 12.9 bits each; this tool's 29-word list gives about 4.9 bits a word. Add more words to compensate, and treat these as convenient rather than high-security.

Privacy

The passphrase is generated locally and never transmitted.

Nothing is stored — it disappears when you refresh.

With no server in the loop, there is no record of your phrase anywhere.

Technical Details

Words3–10 (default 4)
SeparatorsHyphen, dot, underscore or space
Word list29 built-in words
Trailing numberRandom 0–99
Bits per wordAbout 4.9 (log2 of 29)
4-word defaultAbout 26 bits
RandomnessWeb Crypto getRandomValues
Where it runsIn your browser — nothing sent

Standards & references

  • Diceware / EFF wordlist — the benchmark for word passphrases: 7,776 words, about 12.9 bits per word, with a six-word phrase (~77 bits) recommended for real security.
  • Web Crypto — getRandomValues — the cryptographically secure generator used to pick each word at random.
  • NIST SP 800-63B — encourages long passphrases and allows spaces and long inputs — length is what counts, and passphrases are an easy way to get it.

Accuracy & Limitations

The honest headline: with a 29-word list, a 4-word phrase is around 26 bits — fine for low-stakes logins, not for guarding a vault or email. For real security, add words (the effect is large) or use a Diceware tool with a 7,776-word list.

The trailing 0–99 number adds under 7 bits — a small top-up, not a replacement for more words.

Memorability cuts both ways. Because a phrase is easy to remember, it's tempting to reuse it — don't, especially across important accounts.

The words are common on purpose, to be memorable. That's fine in principle because strength should come from the random draw, not obscurity — but here the small list is the binding limit, so lean on word count.

Real-World Use Cases

A password you type by hand

Good for a login you enter often and must remember without a manager open.

Device or Wi-Fi access

A phrase others can read out and type is friendlier than a random string.

A base to strengthen

Start here and push to 7–10 words when you need something meaningfully stronger.

Explaining passphrases

The contrast with Diceware makes the bits-versus-memorability trade-off easy to teach.

When to use it — and when not to

Good for

  • Memorable low-to-medium-stakes passwords
  • Secrets you type by hand and must recall
  • A friendlier alternative to random strings
  • Learning how passphrases work

Not the best choice for

  • High-value secrets like email, banking or a password vault
  • Anything where about 26 bits is not enough
  • A secret you'll store in a manager anyway

For a vault, email or banking password, use the password generator (kept in a manager) or a 6-word Diceware phrase. Here, word count is the lever — push to 7–10 words for a real jump in strength.

Frequently Asked Questions

Why use a passphrase instead of a random password?
Memorability. A handful of real words is far easier to recall and type than a random string, and length is what makes passwords strong — so a long passphrase can be both usable and reasonable, provided the word list is large enough.
How strong is the default passphrase?
About 26 bits for four words plus the trailing number, because the built-in list is only 29 words. That's adequate for low-stakes logins but not for protecting anything valuable — add words to raise it.
Only 29 words — isn't that weak?
Relatively, yes. Each word adds about 4.9 bits versus 12.9 bits in a full 7,776-word Diceware list. The fix is more words: a 7-to-10-word phrase here is much stronger, or use a dedicated Diceware tool for high stakes.
How many words should I use?
More is stronger, roughly 4.9 bits per word. Three or four is fine for casual use; for anything you actually care about, push toward the upper end of the range.
Is the word choice really random?
Yes. Each word is selected with crypto.getRandomValues, the browser's cryptographically secure generator — not a predictable shuffle.
What is the number on the end for?
The random 0–99 adds a little entropy (under 7 bits) and helps satisfy sites that demand a digit. It's a small boost, not a substitute for adding words.
Is my passphrase sent anywhere?
No. It's generated entirely in your browser and never transmitted or stored.
What is Diceware?
A method that picks words at random from a 7,776-word list (the rolls of five dice), giving 12.9 bits per word. EFF publishes a popular version and recommends six words for about 77 bits.
Can I use spaces between words?
Yes, space is one of the separator options. Be aware a few systems trim leading or trailing spaces, so a hyphen or underscore can be safer for compatibility.
Should I reuse a passphrase across accounts?
No. Reuse means one leak unlocks several accounts. Generate a separate phrase per important account, or store random passwords in a manager.
Are common words a weakness here?
Familiar words are fine when the choice is random and the list is large — the attacker still has to guess the combination. The real limit in this tool is the small list size, not the words being common.
Can I actually memorise a six-word phrase?
Usually yes — that's the appeal. Six everyday words form a little scene that sticks, which is why Diceware-style phrases are popular for master passwords.

References

Words are chosen with the browser's secure generator, but the built-in list is only 29 words (~4.9 bits each) — so add words, or use a 7,776-word Diceware list for high-stakes secrets.

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