Is My Password Strong Enough? How to Check (Without Sending It Anywhere)
Most people think their password is strong. Most people are wrong.
The password P@$$w0rd! looks complex. It has uppercase, lowercase, numbers, and symbols. It meets most website requirements. And it would be cracked in seconds by any modern password-cracking tool, because attackers already check for common character substitutions.
Understanding what actually makes a password strong — and testing yours safely — is one of the simplest things you can do to protect yourself online.
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Check Password Strength →How Passwords Get Cracked
Attackers don't just "guess" passwords one at a time. Modern cracking uses GPUs that can test billions of password combinations per second. There are three main attack methods.
Dictionary attacks try every word in massive wordlists — including common passwords, phrases, names, and leaked passwords from previous breaches. The list of the 10 billion most common passwords is publicly available. If your password is a word, name, or common phrase, it's in the list.
Rule-based attacks apply transformations to dictionary words: capitalize the first letter, add numbers at the end, substitute @ for a, 0 for o, 3 for e, and $ for s. The password P@$$w0rd1! feels complex but is just "password1!" with predictable substitutions that every cracking tool checks automatically.
Brute-force attacks try every possible combination of characters. This is where password length becomes critical: each additional character multiplies the number of possibilities exponentially.
How Long to Crack: Password Length vs. Time
These estimates assume a moderately sophisticated attacker with GPU-based cracking capability (approximately 100 billion guesses per second for simple hash types like MD5).
| Password Type | Example | Crack Time |
|---|---|---|
| 6 chars, lowercase | monkey | Instant |
| 8 chars, mixed case + numbers | Monkey12 | Minutes |
| 8 chars, mixed + symbols | M0nk3y!@ | Hours |
| 12 chars, mixed + symbols | M0nk3y!@#$xZ | Weeks to months |
| 16 chars, random | kX9#mPq2$vL8nR4! | Centuries |
| 4-word passphrase | correct horse battery staple | Centuries |
| 5-word passphrase | piano river cloud hammer silk | Millennia+ |
The key insight: going from 8 characters to 16 characters doesn't double the crack time — it increases it by trillions of times. Length beats complexity every time.
Why Passphrases Win
A passphrase is a sequence of random words used as a password. The concept was popularized by the XKCD comic comparing "correct horse battery staple" (44 bits of entropy, easy to remember) versus "Tr0ub4dor&3" (28 bits, hard to remember).
Passphrases work because each random word adds significant entropy. Four words chosen randomly from a list of 7,776 words (like the EFF Diceware word list) produce approximately 51 bits of entropy — strong enough to resist brute-force attacks for centuries. Five words push this even higher. And unlike random character strings, passphrases are actually memorable.
Our secure password generator can create random passphrases using the EFF word list — all generated locally in your browser.
What NIST Recommends in 2025
The National Institute of Standards and Technology (NIST) updated its password guidelines in Special Publication 800-63B, and the recommendations may surprise you.
NIST no longer recommends forced regular password changes. Research showed that requiring frequent changes leads people to choose weaker passwords and make predictable modifications (Password1 → Password2 → Password3). Change passwords only when there's evidence of compromise.
NIST recommends against composition rules that force specific character types (must include uppercase, number, symbol). These rules create false confidence without meaningfully increasing entropy, and often result in patterns like Password1!.
NIST does recommend checking passwords against lists of known breached passwords, supporting passwords up to at least 64 characters, and allowing all printable characters including spaces (which enables passphrases).
The Bottom Line
Make your passwords long (16+ characters or 4+ random words), unique (never reuse across services), and stored in a password manager (so you don't have to remember them). Check your most important passwords with our strength checker. If any would be cracked in less than centuries, change them now.
Then check if those accounts have already been compromised: our email breach checker shows which services have leaked your data — and whether passwords were included in the breach.
Frequently Asked Questions
How long does it take to crack a password?
A 6-character lowercase password: seconds. An 8-character mixed password: hours to days. A 16+ character passphrase: centuries. Length is the single biggest factor. Each additional character multiplies cracking time exponentially.
Is it safe to type my password into an online checker?
Only if it runs entirely in your browser (client-side). Our tool never sends your password anywhere. Never type your real password into a tool that transmits it to a server. Check the browser's Network tab if you're unsure.
Are passphrases better than complex passwords?
Yes. Four random words are both stronger and easier to remember than a short complex password. Passphrases work because length adds entropy exponentially, while character substitutions add very little security.
How often should I change my password?
NIST no longer recommends regular password changes unless there's evidence of compromise. Frequent forced changes lead to weaker passwords. Use strong unique passwords and change them only after a breach.
What makes a password weak?
Under 12 characters, dictionary words, personal info (names, birthdays), common patterns (123456, qwerty), and predictable substitutions (@ for a, 0 for o). The most common passwords are cracked instantly.