How is password entropy calculated?

Entropy in bits equals the password length multiplied by the base-2 logarithm of the character pool size. The pool grows as you add lowercase, uppercase, digits and symbols, so longer passwords with more character types score higher.

What is a good entropy value?

As a rough guide, under 28 bits is very weak, 36 to 60 bits is reasonable, and 60 to 128 bits or more is strong. Aiming for 80 bits or more gives a comfortable margin against offline brute-force attacks.

Is my password sent anywhere?

No. The calculation runs entirely in your browser and your password never leaves your device.

Password Entropy Calculator

Password entropy calculator

Entropy measures how unpredictable a password is, in bits. This tool estimates entropy from your password’s length and the variety of characters it uses, then shows a strength label and an estimated brute-force time to crack at both online and offline attack speeds.

The formula is straightforward: entropy = length × log₂(pool size), where the pool grows with each character type (lowercase, uppercase, digits, symbols). Your password is analysed entirely in your browser and is never uploaded.