// Security
Password Strength Checker online
Check password strength - entropy, crack time estimate, and tips
by
CHUNKY
MUNSTER
MUNSTER
Password Strength Checker measures a password's real strength via its entropy in bits - a measure of how many guesses an attacker would need to find it. This secure password tester detects which character classes you used, multiplies the resulting alphabet size by your password length, and converts the result into a rough brute-force crack-time estimate at 10 billion guesses per second. It works as a comprehensive password entropy calculator for modern security standards.
The math here measures the structural strength of a randomly chosen password from the same alphabet - it cannot detect dictionary words, keyboard walks, or passwords that have appeared in breaches. This charset detection tool provides a score that should be treated as an upper bound: a 70-bit "strong" rating means little if the password is "Summer2026!". Use it to size new passwords, not to bless old ones.
Entropy is computed as length × log2(charset size), where charset size adds 26 for lowercase, 26 for uppercase, 10 for digits, and 32 for symbols. It assumes an attacker knows your character set but not your specific password.
This tool uses a fixed assumption of 10 billion guesses per second - roughly the speed of an offline GPU attack on a fast hash like NTLM. Slow hashes (bcrypt, Argon2) would take years longer; reused or breached passwords are cracked instantly regardless of entropy.
Twelve random characters across all four classes give about 78 bits of entropy, which is well beyond practical brute force today. Length matters far more than complexity - a 16-character passphrase is stronger than an 8-character "P@ssw0rd!".
No. It only measures structural strength. A perfectly random-looking password that has appeared in a public breach is worthless - pair this checker with a "have I been pwned" lookup before reusing anything.
Explore the full suite of Security tools and 290+ other free utilities at Chunky Munster. Ensure your credentials are robust with this Password Strength Checker.