asin()

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 asin() CSS function is a trigonometric function that returns the inverse sine of a number between -1 and 1. The function contains a single calculation that returns the number of radians representing an <angle> between -90deg and 90deg.

Syntax

css

/* Single <number> values */ transform: rotate(asin(-0.2)); transform: rotate(asin(2 * 0.125)); /* Other values */ transform: rotate(asin(pi / 5)); transform: rotate(asin(e / 3));

Parameters

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

number: A calculation which resolves to a <number> between -1 and 1.

Return value

The inverse sine of an number will always return an <angle> between -90deg and 90deg.

If number is less than -1 or greater than 1, the result is NaN.
If number is 0⁻, the result is 0⁻.

Formal syntax

<asin()> = 
 asin( <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 asin() function can be used to rotate elements as it return an <angle>.

HTML

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; }

css

div.box { width: 100px; height: 100px; background: linear-gradient(orange, red); } div.box-1 { transform: rotate(asin(1)); } div.box-2 { transform: rotate(asin(0.5)); } div.box-3 { transform: rotate(asin(0)); } div.box-4 { transform: rotate(asin(-0.5)); } div.box-5 { transform: rotate(asin(-1)); }

Result

Specifications

Specification
CSS Values and Units Module Level 4 # trig-funcs

Browser compatibility

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This page was last modified on ⁨Jul 14, 2025⁩ by MDN contributors.

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