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

  • additions using +
  • subtractions using -
  • multiplication using *
  • division using /

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


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

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