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Password Entropy Meter

Analyzes the mathematical entropy (bits) of passwords to determine absolute resistance to brute-force attacks.

Information Entropy0.0 bits
Character Pool0 chars
Length0 chars
Strength Rating

What is the Password Entropy Meter?

As you type a password, this meter estimates how many bits of entropy it has based on which character types you used and how long it is — a rough proxy for brute-force resistance, calculated entirely in your browser.

How it works

It checks which character classes are present (lowercase, uppercase, digits, symbols) to get a character pool size, then computes entropy as log2(pool size ^ length). It's a pure math estimate — it does not check the password against dictionaries or known-breached password lists, so a long but predictable password can still score deceptively high.

SysAdmin & security use cases

  • Sanity-checking whether a password policy's minimum length actually yields decent entropy.
  • Comparing two candidate passwords side by side before picking one for a shared account.
  • Showing a teammate why 'P@ssw0rd1' is weaker than its character mix suggests.
  • Estimating entropy for a generated API key or token given a known character set.