Password Strength Checker

A password strength checker uses Shannon entropy to quantify how hard a password is to crack. Entropy measures unpredictability based on character set size and password length — higher is harder to guess

The calculator uses the standard published formula for password strength checker uses shannon entropy to quantify how hard a password is to crack. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Entropy (bits) = log₂(charset_size) × length. Each step in the calculation is shown so you can verify the result manually.