Password strength calculator (entropy)

Estimate password entropy (bits) and crack time from length and character types.

Entropy

71 bits

RatingStrong

Character pool62

Crack time (fast attack)5,112 years

Theoretical estimate (10 billion guesses/s). Use a password manager and long, unique passwords.

How the calculation works

Entropy measures unpredictability: entropy = length × log₂(pool size). Each extra bit doubles the guessing effort.

What boosts strength the most?

Length. A longer password beats complex character substitutions.

What is password entropy?

A measure of unpredictability in bits. Each extra bit doubles the guesses needed. Above ~60 bits is strong.

Do letter-for-number swaps help?

Barely — attackers know these tricks (a→4, e→3). Length and randomness matter far more.

Create strong, random passwords with the length and character types you choose. Generated in your browser — nothing is sent.

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Updated on June 18, 2026 · by Rafael Rossi · Methodology & sources