Password Strength Checker
Type a password to get a quick strength rating and an entropy estimate. The password is checked in your browser and is never sent or stored.
Your input stays in your browser. Nothing is uploaded.
Very weak
Entropy bits: 0.0 · Length: 0
About this tool
The rating adds points for length (8, 12, and 16 characters), for mixing upper and lower case, for digits, for symbols, and for an entropy estimate of 60 bits or more. It then removes points for common words and fragments (such as "password", "qwerty", or "123456"), for runs such as "1234" or "abcd", and for three or more repeated characters. Entropy is calculated as length × log₂(pool size), where the pool is 26 lowercase letters, 26 uppercase letters, 10 digits, and 33 symbols. That formula assumes every character was chosen at random, so it overstates the strength of passwords people make up. The checker does not compare your password against lists of breached passwords.
How to use it
- Type or paste the password into the field. It is masked as you type.
- Read the strength level and the entropy in bits.
- If it is weak, make it longer. Length helps more than swapping letters for symbols.
Examples
Short and simple
"sunny" is 5 lowercase letters: 5 × log₂(26) ≈ 23.5 bits, rated very weak.
Common pattern
"Password123!" has every character type, but contains "password", so it drops to weak.
Random 16 characters
A generated 16-character password with all four sets has about 105 bits by this formula and is rated very strong.