How to Create Strong Passwords: Complete Security Guide

In 2026, a password should be at least 15 characters long if it is the only thing protecting an account, and it should be random and unique to that account. That is the minimum set by the US National Institute of Standards and Technology in NIST SP 800-63B, the guideline most security policies are based on. For accounts that matter, such as email, banking and your password manager, a randomly generated password of 16 to 20 characters or a passphrase of six random words, combined with two-factor authentication, is a comfortable margin.

The Password Generator creates passwords from 4 to 64 characters using your browser's cryptographically secure random number generator, with toggles for upper case, lower case, numbers and symbols and an option to exclude look-alike characters. This guide explains the reasoning behind those choices.

What NIST SP 800-63B Says About Passwords

NIST revised its digital identity guidelines as SP 800-63-4, and the password section (SP 800-63B) reverses several rules many people still follow. The key requirements for services that check passwords are:

The reasoning is practical. Composition rules push people towards predictable patterns like Password1!, and forced expiry leads to Summer2025 becoming Autumn2025. Length and randomness are what actually make a password hard to guess, while blocklists catch the passwords attackers try first.

Why Length Beats Complexity

Password strength is often measured in bits of entropy: the number of guesses an attacker would need is about 2 raised to that number. For a truly random password, entropy is the length multiplied by log₂ of the number of possible characters.

The 88-character set is what the Password Generator uses with every option on: 26 lower-case letters, 26 upper-case letters, 10 digits and 26 symbols. Two things stand out. Adding length raises entropy faster than adding character types, and 16 random letters and digits already beat 12 characters with symbols. And every additional bit doubles the work for an attacker, so the 103-bit password is not slightly harder to guess than the 78-bit one; it takes tens of millions of times more guesses.

These figures only apply to passwords that are genuinely random. A 16-character password built from a name, a year and a symbol has far less entropy than its length suggests, because attackers try those patterns first.

Random Passwords vs Passphrases

Both are good choices, for different situations.

Random character strings such as k7#Qm2vX!9pLr4Tz pack the most strength into the fewest characters and are ideal for anything stored in a password manager, where you never type them yourself.

Passphrases such as six randomly chosen words are easier to remember and to type on a phone or TV. The words must be chosen randomly, for example with dice and a published list like the EFF large wordlist, which has 7,776 words. A phrase you invent yourself, or a famous quote, is far weaker because people pick predictable words.

A good rule: use a passphrase for the few passwords you must remember (your password manager's master password, your computer login) and random generated passwords for everything else.

Common Password Mistakes

How to Manage Strong Passwords

Nobody can remember dozens of random passwords, and NIST's guidance assumes you will not try to.

How the Codezyra Password Generator Works

For a site that limits you to letters and digits, simply turn symbols off and increase the length. Pair the generator with the Hash Generator if you are a developer testing how passwords are stored, and remember that real applications should hash passwords with a dedicated slow algorithm such as Argon2, bcrypt or scrypt rather than a plain SHA hash.

Ready to replace a weak password? Open the Password Generator, set the length to at least 16, and save the result straight into your password manager.