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css function

`atan()` CSS function

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The atan() CSS function is a trigonometric function that returns the inverse tangent of a number between -∞ and +∞. The function contains a single calculation that returns an angle between -90deg and 90deg.

Syntax

/* Single <number> values */
transform: rotate(atan(1));
transform: rotate(atan(4 * 50));

/* Other values */
transform: rotate(atan(pi / 2));
transform: rotate(atan(e * 3));

Parameters

The atan(number) function accepts only one value as its parameter.

  • number
    • : A calculation which resolves to a &lt;number&gt; between -∞ and +∞.

Return value

The inverse tangent of a number will always return an angle between -90deg and 90deg.

  • If number is 0⁻, the result is 0⁻.
  • If number is +∞ the result is 90deg.
  • If number is -∞ the result is -90deg.

That is:

  • atan(-infinity) representing -90deg.
  • atan(-1) representing -45deg
  • atan(0) representing 0deg
  • atan(1) representing 45deg
  • atan(infinity) representing 90deg.

Formal syntax

Examples

Rotate elements

The atan() function can be used to rotate elements as it return an angle.

HTML

<div class="box box-1"></div>
<div class="box box-2"></div>
<div class="box box-3"></div>
<div class="box box-4"></div>
<div class="box box-5"></div>

CSS

body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 50px;
}

div.box {
  width: 100px;
  height: 100px;
  background: linear-gradient(orange, red);
}
div.box-1 {
  transform: rotate(atan(-99999));
}
div.box-2 {
  transform: rotate(atan(-1));
}
div.box-3 {
  transform: rotate(atan(0));
}
div.box-4 {
  transform: rotate(atan(1));
}
div.box-5 {
  transform: rotate(atan(99999));
}

Result

Interactive exampleOpen the canonical MDN source to run this embedded demo.

Specifications

SpecificationsStandards references are available on the canonical MDN page.

Browser compatibility

Browser compatibilityCompatibility data is available on the canonical MDN page.

See also