atan2()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2023.
The atan2() CSS function is a trigonometric function that returns the inverse tangent of two values between -infinity and infinity. The function accepts two arguments and returns the number of radians representing an <angle> between -180deg and 180deg.
Syntax
/* Two <number> values */
transform: rotate(atan2(3, 2));
/* Two <dimension> values */
transform: rotate(atan2(1rem, -0.5rem));
/* Two <percentage> values */
transform: rotate(atan2(20%, -30%));
/* Other values */
transform: rotate(atan2(pi, 45));
transform: rotate(atan2(e, 30));
Parameters
The atan2(y, x) function accepts two comma-separated values as its parameters. Each value can be a <number>, a <dimension>, or a <percentage>. Both values must be of the same type, although if they are <dimension> they can be of different units (example: atan2(100px, 5vw) is valid).
y-
The y-coordinate of the point. A calculation which resolves to a
<number>, a<dimension>, or a<percentage>. x-
The x-coordinate of the point. A calculation which resolves to a
<number>, a<dimension>, or a<percentage>.
Return value
Given two values x and y, the function atan2(y, x) calculates and returns the <angle> between the positive x-axis and the ray from the origin to the point (x, y).
Formal syntax
<atan2()> =
atan2( <calc-sum> , <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 |
NaN
Examples
Rotate elements
The atan2() 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
div.box {
width: 100px;
height: 100px;
background: linear-gradient(orange, red);
}
div.box-1 {
transform: rotate(atan2(3, 2));
}
div.box-2 {
transform: rotate(atan2(3%, -2%));
}
div.box-3 {
transform: rotate(atan2(-1, 0.5));
}
div.box-4 {
transform: rotate(atan2(1, 0.5));
}
div.box-5 {
transform: rotate(atan2(1rem, -0.5rem));
}
Result
Specifications
| Specification |
|---|
| CSS Values and Units Module Level 4 # trig-funcs |
Browser compatibility
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