Password Generator

How many bits does a 6-word passphrase have?

77 bits: each word drawn from the 7,776-word list adds about 12.9 bits, and 8 words give 103. With "Include a number", one digit placed after one random word adds a few bits more, for example 83 in total for six words.

Does every password contain each type I checked?

Yes. A password missing one of the checked types is drawn again, so each selected type appears at least once, as sites with composition rules expect. Every password that qualifies stays equally likely.

What does Avoid look-alike characters remove?

6 characters: zero, capital O, one, lowercase l, capital I, and the vertical bar, which are easy to confuse in many fonts. The alphabet gets smaller, so the strength shown drops slightly for the same length.

Are generated passwords stored or logged?

No. They exist only in the page while it is open: no request carries them to our servers, and a reload clears them. Copy a password before generating again, because a new click replaces the list.

How long should a password be?

With all four types checked, 12 characters give about 77 bits, rated strong, and the default 16 give about 103, rated excellent; at 8 characters the page rates it fair and tells you to make it longer. When the password goes into a password manager, use the longest length the site accepts.

How long would it take to guess a password with that many bits?

Each bit doubles the number of possible results. For an attacker testing a trillion guesses per second against a stolen database protected by a fast hash, trying every possibility takes about 38 minutes at 51 bits (the figure shown for 8 characters with all four types), about 4,800 years at 77 bits (12 characters or a 6-word passphrase), and about 320 billion years at 103 bits (16 characters); on average the right one turns up halfway. A site that limits login attempts or stores passwords with a slow hash makes each guess far slower.

How is each character picked, and why does it matter?

Each character comes from a 32-bit value of crypto.getRandomValues, the browser's cryptographic generator. A common shortcut, one random byte modulo 88, would make 80 of the 88 characters 1.5 times as likely as the other 8, because 256 is not a multiple of 88. The page instead discards the rare values above the last full multiple of 88 (about 1 draw in 89 million) and draws again, so every character has the same chance; words are picked from the 7,776-word list the same way.

Is the strength figure exact?

It is the length times log2 of the alphabet size, rounded down: 88 characters with all four types, 82 with "Avoid look-alike characters". Drawing again when a checked type is missing removes a few possibilities; we counted them exactly for every length from 8 to 64 and every combination of types, and the figure shown is never more than 1 bit off, for example 51 shown for 8 characters with all four types, against 50.6 exactly.

Is a passphrase stronger than a random password?

Only with as many bits: 6 words give 77, about the same as 12 random characters, and 8 words give 103, like 16 characters. A passphrase takes longer to type but is easier to remember and to read out, which is why it suits a master password.

What if a site refuses some symbols?

The symbol set cannot be edited, so uncheck "Symbols" and add length instead: 16 letters and digits give about 95 bits, and 20 give about 119. Each password then still holds at least one uppercase letter, one lowercase letter, and one digit.

Does Copy take every password I generated?

Yes. When "How many" is above 1, the button reads "Copy all" and puts every result on the clipboard, one per line, as they are listed in the box above it.

Can it test the strength of a password I already use?

No. The strength line is computed from the settings of each draw (the length and the size of the alphabet or word list), and the page has no field for typing an existing password.

Can it make a 4- or 6-digit PIN?

No: the shortest password is 8 characters. With only "Numbers" checked, 8 digits give about 26 bits, rated weak, which only suits a code protected by an attempt limit, such as a phone or door PIN.