Password Strength Checker
Estimate a password's entropy and how long it might take to crack, checked privately in your browser.
About the Password Strength Checker
Entropy measures how many guesses an attacker might need: length × log₂(size of the character set). This is an upper bound: real attackers try dictionary words, names, dates and common substitutions first, so predictable passwords are weaker than the number suggests. NIST guidance favours long passphrases and checking against breached-password lists over complex composition rules.
The formula
Entropy (bits) = length × log₂(character pool)
Worked example
Example: Strength = Strong (72 bits)
- Input: Password to check: Tr0ub4dor&3.
- Formula: Entropy (bits) = length × log₂(character pool)
- Result: Strength = Strong (72 bits)
Things to keep in mind
- A simple estimate; it can't detect every pattern. Use a password manager and unique passwords for every site.
Questions people ask
Is my password sent anywhere?
No, the check runs entirely on your device.
How long should a password be?
At least 15 characters for important accounts, or a 4–6 random-word passphrase.