Skip to content

The CSS calc() function

Learn how to work with the CSS calc() function

The calc() function lets you perform basic math operations on values, and it’s especially useful when you need to add or subtract a length value from a percentage.

This is how it works:

div {
	max-width: calc(80% - 100px)
}

It returns a length value, so it can be used anywhere you expect a pixel value.

You can perform

One caveat: with addition and subtraction, the space around the operator is mandatory, otherwise it does not work as expected.

Examples:

div {
	max-width: calc(50% / 3)
}
div {
	max-width: calc(50% + 3px)
}

→ Here's my latest YouTube video

→ Get my CSS Handbook

→ I wrote 17 books to help you become a better developer, download them all at $0 cost by joining my newsletter

JOIN MY CODING BOOTCAMP, an amazing cohort course that will be a huge step up in your coding career - covering React, Next.js - next edition February 2025

Bootcamp 2025

Join the waiting list