About the Password Crack Time Calculator
How long would it take to crack your password? This tool estimates the answer for realistic attack scenarios, from a website that limits login attempts to an offline cracking rig running billions of guesses per second against a leaked database. The estimate is based on entropy: the number of characters multiplied by the log₂ of the character set (lowercase, uppercase, digits, symbols), reduced for obvious patterns such as common passwords, repeated characters, keyboard sequences and years.
The maths: an attacker needs on average half of all possible combinations, so time = (charsetlength ÷ 2) ÷ guesses per second. Adding one character multiplies the work by the charset size, which is why length matters far more than swapping an "a" for "@".
Everything is computed in your browser with no network requests, so it is safe to test real passwords, though testing a variant is even safer. Use a password manager to generate long, unique passwords for every account and turn on two-factor authentication wherever it is offered.
How to use the Password Crack Time Calculator
- Type a password (or a similar one) into the box. It is never sent to a server.
- Choose the attack scenario that worries you: an online login attack or an offline attack on a stolen database.
- Read the estimated crack time, the entropy in bits and the strength rating, and compare all scenarios in the table.