Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

The abs() CSS function returns the absolute value of the argument, as the same type as the input.


/* property: abs(expression) */
width: abs(20% - 100px);


The abs(x) function accepts only one value as its parameter.


A calculation which resolves to a number.

Return value

The absolute value of x.

  • if x's numeric value is positive or 0⁺, return x.
  • Otherwise, returns -1 * x.

Formal syntax

<abs()> = 
abs( <calc-sum> )

<calc-sum> =
<calc-product> [ [ '+' | '-' ] <calc-product> ]*

<calc-product> =
<calc-value> [ [ '*' | '/' ] <calc-value> ]*

<calc-value> =
<number> |
<dimension> |
<percentage> |
<calc-keyword> |
( <calc-sum> )

<calc-keyword> =
e |
pi |
infinity |
-infinity |


Positive variables

The abs() function can be used to ensure that a value is always positive. In the following example a CSS custom property --font-size is used as the value of font-size. Wrapping this custom property in abs() will convert a negative value to a positive one.

h1 {
  font-size: abs(var(--font-size));

Control gradient angle of direction

You can also control the gradient direction using abs() function. In the following example, with an angle of -45deg the gradient would start red and transition to blue. By using abs() to make the value positive, the gradient will start blue and transition to red.

div {
  --deg: -45deg;
  background-image: linear-gradient(abs(var(--deg)), blue, red);

Backwards compatible fallback

In older browsers that lack the support for CSS abs() function, you can use the CSS max() function to achieve the same result, as shown below:

p {
  line-height: max(var(--lh), -1 * var(--lh));

We use the max() function to return the largest (most positive) value from a list of two values: var(--lh) or -1 * var(--lh). Irrespective of whether --lh is positive or negative, the calculated return value will always be positive, that is, an absolute number.


CSS Values and Units Module Level 4
# sign-funcs

Browser compatibility

BCD tables only load in the browser

See also