Passphrase Generator

Written byOleh Soloninupdated 5 October 2026

How many words

Separator

Capitalise words

Add a number

Advanced options

Seed

Leave it empty: the browser's cryptographic generator picks the words when you press the button. With a seed the phrase can be rebuilt by anyone who knows the seed, so a seed is no good for a real password.

Result

PassphrasePress "Create a phrase"
Entropy, bits45.2
Average brute-force timeabout 33 minutes of brute force
Length, characters0
Words in the list209
What matters
The list holds 209 words, so each randomly chosen word adds 7.7 bits, and the time is the average at ten billion guesses a second — a GPU rig against a fast hash. A full 7,776-word diceware list gives 12.9 bits a word.

Length beats punctuation

Builds a password out of random words and states its entropy in bits and the average brute-force time.

A password made of four random words is easier to remember and harder to guess than one made of a short word with a digit and an exclamation mark glued on. Attackers know every substitution people make; they cannot know which words came up.

What matters is the number of choices, not the number of characters. Each word drawn from a list of N adds log2(N) bits, and that figure is shown so you can judge the phrase rather than trust it.

How to use

Set how many words the phrase should have.
Pick the separator — it changes the length but not the strength.
Read the entropy in bits: that is the measure of strength, not the length of the string.
For anything important, use more words: each one adds a fixed number of bits.

What each extra word buys

Each row is a run of this calculator with a 209-word list and a two-digit number appended. Every word adds exactly 7.7 bits, because that is the base-two logarithm of 209.

Crack time doubles with every bit, so short phrases fall instantly and long ones do not. Note the weakness too: this word list is small. The classic diceware list of 7,776 words gives 12.9 bits a word, so five of its words are worth roughly eight of these.

Runs of this calculator with a 209-word list and a two-digit number appended.
Words	Entropy	String length	Average crack time
3	29.8 bits	20	about 0 seconds
4	37.5 bits	26	about 10 seconds
5	45.2 bits	33	about 33 minutes
6	52.9 bits	41	about 4.8 days
8	68.3 bits	53	about 577 years

What this calculator shows

The passphrase with your separator and options
The entropy in bits and the size of the word list
How long brute force would take at ten billion guesses a second

What to keep in mind

Entropy counts only the choices actually made. Adding characters that were not chosen randomly adds length, not strength.
The crack time is the average — half the full search — against a fast hash on GPUs. bcrypt and Argon2 slow an attack down many times over, but by how much depends on their settings and the hardware.

FAQs

How many words are enough?

Six random words from this list give 46.2 bits, or 52.9 with the two-digit number. From a full diceware list of 7,776 words, five words already give 64.6 bits.

What is entropy in bits?

The base-two logarithm of the number of equally likely possibilities. Each extra bit doubles the work an attacker has to do.

Does capitalising the first letter help?

Barely. If the rule is predictable — and capitalising every word is predictable — it adds almost nothing. A random extra word adds far more.

Is it safe to generate a password in a browser?

The phrase never leaves your device here. For a real password, leave the seed empty so the browser's cryptographic generator picks the words. A seed a person makes up rebuilds the phrase exactly, and the phrase is no stronger than the seed. Store the result in a password manager.

Why does this list give only 7.7 bits a word?

Because it holds 209 words, and 7.7 is the base-two logarithm of 209. The classic diceware list has 7,776 words and gives 12.9 bits, so five of its words are worth about eight of these.

How can a long phrase be weaker than a short password?

Because strength comes from the number of possibilities, not the number of characters. Five random words from a 209-word list plus a random two-digit number is 45 bits across 33 characters (the words alone give 38.5); eight random characters from the 94 printable ones give 52 bits in far less space.

Worked example

Five words and a number

Input: seed "unitools", 5 words, hyphen separator, a number on the end

Output: cinema-belt-brick-alert-cotton-15

Note: This example comes from the seed "unitools" and is published on this page — do not use it as a password. 45 bits is the strength of randomly chosen words: with no seed the calculator draws them from the cryptographic generator. That is fine for an account with rate limiting behind it and weak against an offline attack on a leaked fast-hash database.

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