Password Entropy Explained

Learn what password entropy is, how it’s calculated, and why it determines real security strength.

What Is Password Entropy?

Password entropy is a measure of unpredictability — the number of bits representing how hard a password is to guess. The more random the characters or words, the higher the entropy.

If you're unsure whether long passwords or passphrases are better, our passphrases vs passwords guide shows why four random words can outperform short symbol-heavy passwords.

How Entropy Is Calculated

Entropy increases exponentially with length. A password generator like StrongPass increases entropy by adding randomness — far superior to patterns like keyboard sequences.

Attackers use brute-force and dictionary attacks to guess passwords. Higher entropy makes these attempts practically impossible.

Why Entropy Matters

• Prevents brute-force attempts • Avoids predictable patterns • Helps resist credential stuffing • Makes passwords harder to guess, even with leaked data

Entropy in Passphrases vs Passwords

A passphrase like Battery–Window–Clock–Dolphin has massive entropy because each word multiplies the search space. Learn when to choose passphrases in our passphrase comparison guide.

Best Practices for High-Entropy Passwords

Use: • 16–24 characters • Randomness • Multiple character sets • No repetitions or personal clues See our advice in how to create strong passwords.

For sensitive logins, follow the settings recommended in: high-risk account password settings.