16 Character Password Generator

Create a random 16-character password that satisfies almost every website's complexity rules.

Why 16 characters?

Sixteen characters is a strong practical length for randomly generated passwords: long enough to resist offline cracking, short enough to be accepted by nearly every login form. With all four character types enabled, the pool size is 91 (26 lowercase + 26 uppercase + 10 digits + 29 symbols — see the methodology page for the exact character sets). Entropy in bits is length × log2(pool size), so a 16-character password from this pool works out to 16 × log2(91) ≈ 16 × 6.51 ≈ 104 bits. That figure is the base-2 logarithm of how many equally likely 16-character strings exist in that pool — the size of the space an attacker who does not already know the password would have to search, assuming it was chosen uniformly at random and isn't reused anywhere else.

Meets standard complexity rules

The generator guarantees at least one character from every type you enable, so the result passes validation rules that demand an uppercase letter, a number and a symbol — without you having to regenerate repeatedly.

What 16 characters resists, and when you need more or less

At roughly 104 bits of entropy, a truly random 16-character password sits far above the point where guessing every possibility becomes a realistic strategy — the search space doubles with every extra bit, so 104 bits is an astronomically larger space than the 60–70 bits typical of shorter, human-chosen passwords. What it does not protect against is a password that leaks in a data breach, gets reused on a second site, or is typed into a phishing page; entropy only describes resistance to guessing, not resistance to theft.

For random passwords, length matters more than adding character types. Going from 12 to 16 characters adds about 26 bits (four extra characters at ~6.51 bits each). Going from a 62-character pool (letters and digits only) to the 91-character pool by adding symbols adds under 1 bit per character — useful, but not a substitute for length. If a site accepts longer passwords, use them for your highest-value accounts (primary email, password manager master password, financial and crypto accounts) and reserve 16 characters as the everyday default.

16 characters vs. a PIN vs. a passphrase

These tools solve different problems. A numeric PIN (see the PIN generator) belongs on device lock screens and payment cards — contexts where hardware enforces a lockout after a handful of wrong attempts, so the PIN never has to resist unlimited guessing. A PIN should never protect an online account: there is no hardware limiting how many times a script can try a password against a login form, so the account needs a search space measured in tens of bits more than any PIN can offer. A 16-character random password is built for exactly that unlimited-guessing scenario. A passphrase of random dictionary words trades some entropy density for memorability — six words from the EFF long wordlist give about 78 bits, somewhat less than a 16-character random string, but easier to type by hand.

Password length comparison: 12 vs. 16 vs. 20 characters

Common mistakes that undo a strong password

• Reusing the same password across multiple sites — one breach then compromises every account that shares it.
• Basing it on a name, word or birthday, even with digits or symbols appended — pattern-based guessing tries these first.
• Sequential or keyboard-adjacent runs like 1234, qwerty or asdf, which collapse the effective search space far below the character count.
• Writing it on a sticky note, in an unencrypted note file, or anywhere else visible to someone with desk or screen access.
• Trusting symbols and capitals to compensate for a short length — as shown above, length contributes far more entropy than character variety.
• Leaving a character type disabled when the site allows it, which shrinks the pool size for no security benefit.

How the randomness is produced

Every character comes from window.crypto.getRandomValues(), the browser's cryptographically secure random number source, combined with rejection sampling so each character in the pool has an exactly equal chance of being chosen. Generation happens entirely in JavaScript in your browser tab; nothing is sent to a server, logged, or stored. See the Security page for how to verify this yourself, and the Methodology page for the full entropy math.

Need a different length?

Drag the length slider to anything between 4 and 64 characters, or use the strong password generator for a longer default.