How long would your password take to guess?
Most estimators assume one guessing speed. In reality the speed depends entirely on how the password is stored on the other end. The same password that falls in seconds against a leaked fast-hash database can hold for centuries if the site used a slow hash like bcrypt. This runs entirely in your browser — nothing you type is sent anywhere or stored.
Time to guess, by how it is stored
Assuming an attacker who knows the character set and brute-forces it (average = half the keyspace). Real human passwords fall far faster; see the note.
| Attack scenario | Guesses / sec | Average time to guess |
|---|
Frequently asked questions
How long does it take to crack a bcrypt password?
With bcrypt at cost factor 12 a single modern GPU manages only a few thousand guesses per second, so a random 10+ character password can take years to centuries, versus tens of billions of guesses per second against a fast hash.
Does bcrypt stop GPU cracking?
No. bcrypt does not block GPU cracking, it slows it by design. Its deliberate iteration cost turns a seconds-long fast-hash crack into years, but a weak or reused password can still fall.
Why does the same password crack in seconds with MD5 but years with bcrypt?
MD5 and NTLM are fast hashes a GPU computes billions of times per second; bcrypt, scrypt and Argon2 are deliberately slow, cutting the guess rate to thousands per second. The password is identical; the storage method changes the answer by orders of magnitude.
How many bits of entropy is a safe password?
Against an offline fast-hash GPU attack, 60 or more bits (about a 10-character fully random password) is a reasonable floor. Against a properly configured slow hash like bcrypt, less entropy is needed because the hash itself supplies the slowdown.
Is NTLM safe for storing passwords?
No. NTLM is an unsalted fast hash crackable at tens of billions of guesses per second per GPU, so even complex passwords can fall in hours to days. Use bcrypt, scrypt or Argon2id instead.
What is the difference between an online and offline password attack?
An online attack guesses against a live login and is throttled to a handful of tries per second; an offline attack runs against a stolen hash database at the full speed of the attacker's hardware. Offline attacks are where the choice of hash matters most.
Why do password strength checkers disagree on crack time?
Because each assumes a different attacker and hardware. Online throttling, offline fast-hash cracking and offline bcrypt cracking can differ by more than ten orders of magnitude for the same password.
Read: how passwords are actually cracked →
Tool: OWASP password-hashing parameter recommender →