What does the Password Entropy Calculator measure?

This calculator estimates the theoretical entropy of a password in bits. Entropy represents how many possible combinations an attacker may need to try when brute-forcing a password. Higher bit values generally indicate stronger passwords.

How do I choose the Character Set Size value?

Character Set Size is the number of unique characters that could appear in the password. For example, use 26 for lowercase English letters, 52 for upper and lowercase letters combined, 62 for letters and numbers, or 94 for most printable ASCII characters. Choose the value that best matches the types of characters actually used in the password.

What formula does this calculator use?

The calculator uses the formula password_length * (log(character_set_size) / log(2)). This converts the logarithm into base 2 and returns the estimated entropy in bits. The final value is rounded to 2 decimal places.

Why does password length matter so much?

Each additional character increases the number of possible combinations exponentially. A longer password with a moderate character set can often be stronger than a short password with many symbol types. Increasing length is one of the most effective ways to improve entropy.

Can two passwords with the same entropy have different security levels?

Yes. Entropy calculations assume passwords are randomly generated and uniformly distributed across the character set. Human-created passwords may follow predictable patterns, making them weaker than the calculated entropy suggests.

When should I use this calculator?

Use this calculator when evaluating password policies, estimating brute-force resistance, or comparing password complexity options. It is useful for security planning, IT administration, and understanding how password composition affects theoretical strength.

Security & Privacy

Password strength checkers, hash generators, encryption tools, and privacy utilities.

Password Entropy Calculator

Estimates password entropy strength in bits based on password length and character set size.

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