abs()

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

Syntax

css

/* abs( <calc-sum> ) */
abs(20% - 100px)
abs(var(--gradientAngle))

Parameters

The abs() function accepts one parameter.

<calc-sum>
- : An expression or calculation that resolves to a {{cssxref("number")}}, a {{cssxref("dimension")}}, a {{cssxref("percentage")}} or a {{cssxref("calc-keyword")}}.

Return value

The absolute value of <calc-sum>.

If <calc-sum>'s numeric value is positive or 0⁺, the function returns <calc-sum>.
Otherwise, it returns -1 * <calc-sum>.

Formal syntax

Examples

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 {{CSSxRef("font-size")}}. Wrapping this custom property in abs() will convert a negative value to a positive one.

css

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.

css

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

Backwards compatible fallback

In browsers that lack support for CSS abs() function, you can use the CSS {{CSSxRef("max")}} function to achieve the same result:

css

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

We use the {{CSSxRef("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.