What Makes a Strong Password? How to Create and Test Password Security

In 2024, "123456" was still one of the most commonly used passwords on the internet. Despite constant warnings, weak passwords remain the single biggest cause of account breaches worldwide. This guide explains exactly what makes a password strong — and what doesn't.

How Password Cracking Actually Works

Before we talk about strength, it helps to understand how attackers crack passwords. They use three main methods:

• Brute force attacks — Software tries every possible character combination, starting with the shortest. A 6-character all-lowercase password has about 300 million combinations. A modern GPU can try billions of guesses per second — meaning a 6-character password can be cracked in under a second.
• Dictionary attacks — Instead of random combinations, the attacker tries words from a dictionary, common passwords, and known leaked passwords first. If your password is a real word or appeared in any previous data breach, it will be cracked very quickly.
• Credential stuffing — Attackers take username/password combinations from one breach and try them on other services. If you reuse passwords across sites, one breach compromises all your accounts.

The Four Factors That Determine Password Strength

1. Length — The Most Important Factor

Every additional character in a password exponentially increases the number of possible combinations. Here's how dramatically length matters:

• 6 characters (lowercase only) — cracked in under 1 second
• 8 characters (mixed case + numbers) — cracked in about 8 hours
• 12 characters (mixed case + numbers + symbols) — cracked in 34,000 years
• 16 characters — effectively uncrackable with current technology

The minimum for any account today is 12 characters. Aim for 16+.

2. Character Variety

Using a mix of uppercase letters, lowercase letters, numbers, and special characters multiplies the possible combinations at each character position. An 8-character password using only lowercase letters has about 200 billion combinations. Add uppercase, numbers, and symbols and that jumps to over 6 quadrillion.

3. Randomness (Entropy)

A long password isn't automatically strong if it follows predictable patterns. Password123! is 12 characters with mixed types — but it's one of the first things a dictionary attack tries. Similarly, Qwerty1234! looks complex but follows a keyboard pattern that attackers know well.

True password strength comes from randomness — characters that don't follow any pattern a human or algorithm could predict.

4. Uniqueness

Even a perfectly strong password becomes a liability if you use it on multiple sites. When one site gets breached (and breaches happen constantly), attackers immediately try those credentials everywhere else. Every account needs its own unique password.

Passphrases: Strong AND Memorable

A passphrase — a sequence of random words — is one of the best password strategies available. Consider:

correct-horse-battery-staple

This 28-character password is extremely long (high entropy), easy to remember, and far stronger than P@s5w0rd! despite being easier to type. It's resistant to both brute force and dictionary attacks because the combination of four random words is statistically unlikely to appear in any dictionary.

The key is that the words must be genuinely random — not a phrase from a song, book, or personal memory.

Common Password Mistakes to Avoid

• Using your name, birthday, or pet's name
• Using the same password on multiple sites
• Simple substitutions like 3 for e or @ for a — attackers account for these
• Adding ! or 1 at the end of a weak word
• Using passwords shorter than 12 characters
• Using any word that appears in a dictionary
• Using your username as part of your password

How to Test Your Password Strength

A free password strength checker analyzes your password against multiple criteria — length, character variety, entropy, and common patterns — and gives you an immediate strength rating. It tells you whether your password is weak, fair, strong, or very strong.

A reputable password checker runs entirely in your browser and never sends your password to any server. Always verify this before testing a real password in any online tool.

Test Your Password Strength Free →

Building a Sustainable Password Strategy

Use a Password Manager

Tools like Bitwarden (free), 1Password, or Dashlane generate and store unique, strong passwords for every account. You only need to remember one master password. This is the single highest-impact change most people can make to their security.

Enable Two-Factor Authentication (2FA)

Even if a password is compromised, 2FA stops attackers from accessing the account without physical access to your phone or authentication app. Enable it on every account that supports it — especially email, banking, and social media.

Change Passwords After Breaches

If a service you use announces a breach, change your password on that service immediately — and on any other service where you used the same password. You can check if your email has appeared in known breaches at haveibeenpwned.com.