Password Strength Calculator
Estimate password strength (entropy in bits) and time to crack from length and character set.
71 bits
Entropy
| Entropy | 71 bits |
| Combinations | 3,226,266,762,397,900,000,000 |
| Crack time (10¹⁰/s) | 5,115 years |
The password strength calculator estimates your password's entropy in bits and a rough time to crack it based on its length and character set. It shows clearly how much length and character variety really affect security.
How the calculator works and what it’s for▾
How strength is calculated
Entropy follows entropy = length × log2(character set). The more character types you use and the longer the password, the more bits and the more possible combinations.
The crack time assumes 10 billion guesses per second. This is an indicative figure used to illustrate the difference between passwords.
What you enter and what you get
Enter the password length in characters and choose the character set used. You get the entropy in bits, the number of possible combinations and an estimated crack time in years.
Over 80 bits is considered strong, at which point a brute-force attack is effectively impractically slow.
Who benefits from it
It suits anyone who wants to test the strength of a password scheme or demonstrate why length matters more than mixing characters.
It is also useful in teaching and security guidance for showing concrete numbers.
Good to know
The calculator only estimates the theoretical time against a brute-force attack. It does not recognise common passwords, dictionary words or leaked credentials, which are cracked far faster.
Never type your real password into any online tool. Estimate strength from length and character types, not from an actual credential.
🔄 Reviewed June 2026
Frequently asked questions
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