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Password Entropy Calculator

Bits of entropy from charset and length.

Compute the bits of entropy of a password from the size of the character set drawn from (lowercase, uppercase, digits, symbols) and the password length, plus the brute-force time at a chosen guesses-per-second rate.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Entropy = length · log₂(charset).
Brute-force seconds ≈ 2^entropy / 2 / guesses_per_sec.

In depth

Compute the bits of entropy of a password from the size of the character set drawn from (lowercase, uppercase, digits, symbols) and the password length, plus the brute-force time at a chosen guesses-per-second rate.