What Is Password Entropy and Why Does It Matter?

Password entropy is a way to describe how difficult a password is to guess. In practice, the most useful way to increase it is to use a long, random password that is unique to one account.

Why randomness matters

Attackers do not guess every possible string in a perfectly random order. They often begin with common words, names, dates, and predictable patterns. A password such as Summer2026! may look varied, but it follows a pattern attackers can prioritize.

A password generated from a large set of characters without a predictable pattern gives an attacker less useful information. Create one with the Strong Password Generator, then store it in a password manager.

Length is important too

Adding length increases the number of possible combinations. A longer random password is normally more valuable than a short password with a few cosmetic substitutions. Use the maximum length a service accepts, while also following its character requirements.

Entropy is not the whole story

Even a strong password cannot fully protect an account if it is reused, entered into a phishing site, or exposed in a breach. Use a different password for every service and enable MFA or passkeys where available.

FAQ

Does adding one symbol make a password secure?

Not by itself. Length, randomness, and uniqueness work together. Avoid predictable patterns and password reuse.

Should I calculate password entropy myself?

Usually no. Use a reputable generator or password manager, choose a long password, and keep it unique for each account.