Readers like you help support MUO. When you make a purchase using links on our site, we may earn an affiliate commission. Read More.

Even if you know next to nothing about cybersecurity, you probably realize how important it is to use strong passwords. This is known as password entropy. But what does that mean? What makes a password strong? And is it actually possible to measure password strength?

Why Is Password Entropy Important?

The measure of password strength is referred to as password entropy. Password entropy quantifies the unpredictability and randomness of a password: the higher the entropy, the stronger the password. Obviously, a password like "qwerty123" has very low entropy, while a password that is made up of random letters, digits, and special characters has rather high entropy.

Why is entropy important, anyway? The higher the entropy, the less vulnerable you are to a variety of cyber threats, such as brute-force attacks, in which a threat actor uses automated software to figure out your password. Then there are also rainbow table attacks, which revolve around utilizing tables of hashed passwords to gain unauthorized access.

In fact, you may have noticed that many online platforms nowadays demand strong passwords, and won't let you sign up unless you create one. There's a good reason for these requirements: they're there to enhance your security, and make it more difficult for a hacker to crack your password.

How to Calculate Password Entropy

Password symbol on white background

How do you calculate password entropy, and determine how strong a password is, then? There's actually a very simple formula: E = log2 (RL).

"E" stands for entropy, which is the output of the equation. "R" represents the range of characters that can be used in a password, while "L" signifies length, or the number of characters. Lastly, "Log2" is the mathematical formula used to convert the total number of combinations to bits.

If you're not good at math, or find this to be too complicated, there are several online password entropy calculators. Omni Calculator is very good and easy to use. All you have to do is enter how many lower case Latin letters, upper case Latin letters, digits, and special characters are in your password. The calculator will do the rest.

Measure Password Strength to Protect Yourself

You can take all the precautions in the world, but if your password is weak, you are exposed to cybercriminals. Creating a strong one is imperative, and you can only do that if you know how to calculate password entropy.

Also, make sure you never reuse passwords, change them from time to time, and utilize two-factor authentication to create another powerful layer of security.