How to Create Strong Passwords That Actually Protect You

The average person has over 100 online accounts. Reusing the same password across even a fraction of them means one data breach can cascade into dozens of compromised accounts. Yet password reuse remains the single most common security mistake people make.

Strong passwords aren’t about replacing letters with symbols or tacking a number on the end. They’re about mathematical unpredictability. This guide explains how attackers crack passwords, what actually makes one strong, and practical methods to create and manage them. Check any password instantly with our Password Strength Checker or generate one with our Password Generator.

Password Entropy Explained

Entropy measures how unpredictable a password is, expressed in bits. Higher entropy means more possible combinations an attacker must try.

The formula:

Entropy = log2(pool_size ^ length)

Where pool_size is the number of possible characters and length is the number of characters in the password.

Character pool sizes:

Character Set	Pool Size	Example
Lowercase only	26	abcdefgh
Lowercase + uppercase	52	aBcDeFgH
Letters + digits	62	aB3dE5gH
Letters + digits + symbols	95	aB3$E5g!

Entropy examples:

Password	Length	Pool	Entropy (bits)
password	8	26	37.6
Password1	9	62	53.6
P@ssw0rd!	9	95	59.1
correct horse battery staple	28	27	133.2

The 28-character passphrase has over twice the entropy of a short password packed with symbols. Length beats complexity every time.

What the numbers mean in practice:

• Below 40 bits: Cracked in seconds to minutes
• 40-59 bits: Cracked in hours to days with modern GPUs
• 60-79 bits: Cracked in weeks to years
• 80+ bits: Effectively uncrackable with current technology

How Attackers Crack Passwords

Understanding attack methods reveals why certain passwords fail.

Brute Force

The attacker tries every possible combination of characters. A modern GPU cluster can attempt over 100 billion MD5 hashes per second. An 8-character lowercase password (26^8 = 208 billion combinations) falls in about 2 seconds.

Adding uppercase, digits, and symbols increases the pool, but the real defense is length. Each additional character multiplies the total combinations by the pool size.

Dictionary Attacks

Instead of trying every combination, attackers use wordlists containing millions of common passwords, English words, names, dates, and keyboard patterns. The wordlists include predictable substitutions: @ for a, 0 for o, 1 for i, $ for s.

This is why P@ssw0rd isn’t clever. It appears in every dictionary attack wordlist. So do Monkey123, iloveyou, qwerty, and anything based on a single English word with predictable modifications.

Credential Stuffing

Attackers take email/password pairs leaked from one breach and try them on other services. If you use the same password for your email and your bank, a breach at a low-security forum compromises your financial accounts.

Over 15 billion credentials are publicly available from past breaches. Credential stuffing is automated—bots can test thousands of accounts per minute.

Rainbow Tables

Precomputed tables that map hashes back to plaintext passwords. A rainbow table for all 8-character alphanumeric passwords can be generated once and used to crack any hash instantly. Salted hashing (used by modern systems) defeats rainbow tables, but older databases without salting remain vulnerable.

Social Engineering

No amount of password strength helps if an attacker tricks you into revealing it. Phishing emails, fake login pages, and phone scams bypass technical protections entirely. This is one reason two-factor authentication matters: even a stolen password isn’t enough to log in.

What Makes a Password Strong

Based on how attacks work, a strong password has these properties:

1. Long. At minimum 12 characters. 16 or more is better. Each additional character makes brute force exponentially harder.

2. Unpredictable. Not based on dictionary words, names, dates, or keyboard patterns. Random characters or multiple unrelated words strung together.

3. Unique. Used on exactly one account. Reusing a strong password across sites negates its strength the moment any one site is breached.

4. Not a known pattern. Substituting symbols for letters (@ for a, $ for s) doesn’t help when every cracking tool already accounts for these substitutions.

The Passphrase Technique

Passphrases use multiple random words to create long, memorable passwords. The concept was popularized by the XKCD comic “correct horse battery staple” and is backed by the math.

How to create a passphrase:

1. Pick 4-6 words at random from a large wordlist (2,000+ words). Don’t pick words that form a natural phrase or sentence.
2. Combine them with spaces or a separator character.
3. Optionally capitalize one word or add a number for sites that require mixed character types.

Examples:

• blanket river compass anchor (4 words, ~51 bits from a 2,048-word list)
• Blanket-river-compass-anchor-9 (modified for complexity requirements, even higher entropy)
• telescope marble canyon freight violin (5 words, ~64 bits)

Why this works: A 4-word passphrase from a 2,048-word dictionary has 2,048^4 = approximately 17.6 trillion possible combinations. That’s equivalent to a random 11-character password using all character types, but far easier to type and remember.

Important: The words must be chosen randomly. If you pick words that are personally meaningful (your pet’s name, your street, your birthday), the effective entropy drops because an attacker can narrow the search space using public information about you.

Password Manager Benefits

A password manager is a tool that generates, stores, and auto-fills unique passwords for every account. You memorize one master password, and the manager handles the rest.

Why use one:

• Unique passwords everywhere. Each account gets a different random 20+ character password. A breach at one site affects nothing else.
• No memory burden. You don’t need to remember xK#9mP2$vL for every site. The manager fills it in automatically.
• Encrypted storage. Passwords are encrypted with your master password using AES-256 or similar. Even if the vault file is stolen, it’s useless without the master password.
• Phishing resistance. Auto-fill only works on the correct domain. A fake login page at g00gle.com won’t trigger the auto-fill for google.com.

Popular options include 1Password, Bitwarden (open source), and KeePass (local-only). Most offer browser extensions and mobile apps for cross-device access.

The master password matters most. Since it protects everything, make it a strong passphrase of 5+ words that you can reliably type from memory.

Practical Password Strategy

Here is a concrete approach that balances security with usability:

1. Install a password manager. Pick one and commit to it.
2. Create a strong master passphrase. 5+ random words. Write it down and store it in a physically secure location while you memorize it.
3. Generate unique passwords for every account. Use the manager’s generator set to 16-20 random characters.
4. Enable two-factor authentication on critical accounts: email, banking, cloud storage, and the password manager itself.
5. Audit existing passwords. Most managers flag reused and weak passwords. Work through them over time, changing the worst ones first.

Test Your Password Strength

Our Password Strength Checker analyzes any password for entropy, pattern detection, and estimated crack time. Need a new one? The Password Generator creates random passwords and passphrases at any length and complexity level.

Frequently Asked Questions

How long should my password be?

At minimum 12 characters for random passwords or 4 words for passphrases. For high-value accounts like email, banking, and your password manager, aim for 16+ characters or 5+ word passphrases. The computational cost of brute force grows exponentially with each added character, so even a few extra characters make a measurable difference.

Are passphrases really stronger than complex short passwords?

Yes, when the words are chosen randomly. A 4-word passphrase from a 7,776-word list (like Diceware) has about 51 bits of entropy, comparable to a randomly generated 10-character mixed-case password. A 5-word passphrase jumps to 64 bits. The advantage is memorability: most people can remember four random words far more reliably than a string like kX8#mQ2$pL.

Should I change my passwords regularly?

The old advice of changing passwords every 90 days is outdated. NIST (National Institute of Standards and Technology) updated its guidelines in 2017 to recommend against mandatory periodic changes unless there’s evidence of compromise. Frequent forced changes lead to weaker passwords as people resort to predictable patterns like incrementing a number. Use a strong unique password and change it only if the service reports a breach.

Is two-factor authentication enough to protect a weak password?

Two-factor authentication (2FA) adds a significant layer of protection, but it doesn’t make weak passwords safe. SIM-swapping attacks can defeat SMS-based 2FA. Phishing kits can capture both passwords and TOTP codes in real time. Use 2FA as an additional layer on top of a strong password, not as a replacement for one. Hardware security keys (like YubiKey) provide the strongest second factor.

What if I need to share a password with someone?

Never send passwords through email, text messages, or chat. Use your password manager’s secure sharing feature, which encrypts the password in transit and lets you revoke access later. If you must share temporarily, use a service that creates a self-destructing link that expires after one view or a set time period. Change the password after the other person no longer needs access.