Security basics
Passphrase vs. Password Entropy: Understanding Security Differences
Entropy measures the unpredictability of passwords and passphrases. This guide explains how passphrases offer higher entropy and better security compared to traditional passwords, even with fewer characters.
1 min readUpdated: 02/16/2026Author: GeneratePasswordTo Editorial Team
What is Entropy in Passwords?
Entropy is a measure of randomness in a password or passphrase. Higher entropy means greater resistance to brute-force attacks. Traditional passwords often have lower entropy due to predictable patterns or limited character sets.
Passphrases, which are longer sequences of words or phrases, typically have higher entropy because they incorporate more characters, including spaces and non-alphanumeric symbols. This complexity makes them harder to guess or crack.
Entropy calculations use formulas like $ \text{Entropy} = \log_2(N^L) $, where $ N $ is the number of possible characters and $ L $ is the length. Passphrases usually outperform passwords in this metric.
- Entropy determines how hard a password is to crack.
- Passphrases increase entropy by using more characters and words.
- Traditional passwords often lack the randomness needed for high entropy.