Password Strength Checker
Test your password with real-time entropy analysis, crack time estimates, and actionable improvement tips.
How It Works
Entropy Analysis
Calculates the information entropy of your password based on character pool size and length.
Crack Time Estimate
Estimates how long a brute-force attack would take at 10 billion guesses per second.
Pattern Detection
Identifies common patterns like dictionary words, keyboard walks, repeated characters, and sequences.
100% Client-Side
Your password never leaves your browser. No network requests, no logging, no tracking.
FAQ
Is my password uploaded to a server?
No. Everything runs in your browser using JavaScript. Your password is never transmitted anywhere. You can verify by checking the network tab in your browser's developer tools.
What is password entropy?
Entropy measures the unpredictability of a password in bits. A password with 80+ bits of entropy
is considered very strong. The formula is: entropy = log2(pool_size^length).
How is crack time calculated?
We estimate based on 10 billion guesses per second (GPU-accelerated brute force). Real-world attacks may be faster or slower depending on the hashing algorithm used.
Is a long password always better?
Length is the strongest factor, yes. A 16-character password from a large character set is exponentially harder to crack than an 8-character one. But avoid using common phrases or patterns even in long passwords.
How Passwords Get Cracked in 2026
Password cracking has evolved far beyond simple guessing. Modern attackers use GPU-accelerated brute force that can test 10 billion password combinations per second using hardware that costs under $5,000. At that speed, an 8-character password using only lowercase letters falls in under 3 seconds. Add uppercase, numbers, and symbols and you buy more time — but not as much as you'd think.
Dictionary attacks are the first thing any cracker tries. They run through lists of the most common passwords — "password123," "qwerty," "letmein" — and variations with common substitutions like @ for a, 3 for e, and 0 for o. These substitutions feel clever but every cracking tool has them built in. If your password is "P@ssw0rd!" you're not fooling anyone.
Rainbow tables are precomputed lookup tables that map hashed passwords back to their plaintext. If a website stores passwords as unsalted MD5 or SHA-1 hashes and gets breached, attackers can look up millions of passwords instantly without any computation. Modern password storage uses salted bcrypt or Argon2 specifically to defeat rainbow tables, but many older systems still use weak hashing.
Credential stuffing is the most common attack in practice. Attackers take username/password pairs leaked from one breach and try them on other services. If you reuse the same password across Gmail, Netflix, and your bank, a single breach exposes all three. This is why unique passwords per service matter more than password complexity.
What Makes a Password Actually Strong
Password strength comes down to one concept: entropy — the mathematical unpredictability of your password measured in bits. Every bit of entropy doubles the number of guesses an attacker needs. A password with 40 bits of entropy requires about 1 trillion guesses. A password with 80 bits requires over a sextillion guesses — more than any current hardware can process in a human lifetime.
Entropy depends on two factors: the size of the character pool you draw from, and the length of the password. Using lowercase letters only gives you a pool of 26 characters. Add uppercase (52), numbers (62), and symbols (95). But length matters exponentially more than pool size. A 20-character lowercase password has more entropy than a 10-character password using all character types.
The best practical approach in 2026 is passphrases: four or five random words strung together, like "correct horse battery staple" (but actually random — don't use that one, it's famous). A four-word passphrase from a 7,776-word dictionary has about 51 bits of entropy. Five words gives you 64 bits. Six words gives you 77 bits. They're easier to remember and harder to crack than short complex passwords.
Password Managers: The Real Solution
No human can remember unique, high-entropy passwords for 50+ accounts. Password managers solve this by generating and storing random passwords for every service, locked behind one strong master password. The major options — 1Password, Bitwarden, and KeePass — all use AES-256 encryption on your vault. Bitwarden is open-source and free. 1Password has better UX and costs $3/month.
The most important thing you can do for your security in 2026 is use a password manager with unique passwords per site, enable two-factor authentication on your email and financial accounts, and never reuse passwords across services. This tool helps you understand how strong your passwords are — but the real defense is never relying on a single password to protect anything important.