The exp() CSS function is an exponential function that takes a number as an argument and returns the mathematical constant e raised to the power of the given number.

The mathematical constant e is the base of natural logarithms, and is approximately 2.718281828459045.

The exp(number) function contains a calculation which returns the same value as pow(e, number).

Syntax

/* A <number> value */
width: calc(100px * exp(-1)); /* 100px * 0.367879441171442 = 36.8px */
width: calc(100px * exp(0)); /* 100px * 1 = 100px */
width: calc(100px * exp(1)); /* 100px * 2.718281828459045 = 271.8px */

Parameters

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

number

A calculation which resolves to a <number>. Representing the value to be raised by a power of e.

Return value

Returns a non-negative <number> representing e^number, which is the result of calculating e raised to the power of number.

• If number is -Infinity, the result is 0.
• If number is 0, the result is 1.
• If number is 1, the result is e (i.e., 2.718281828459045).
• If number is Infinity, the result is Infinity.

Formal syntax

<exp()> = 
  exp( <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 exp() function can be used to rotate elements as it return a <number>.

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(calc(1turn * exp(-1))); /* 0.3678794411714423turn */
}
div.box-2 {
  transform: rotate(calc(1turn * exp(-0.75))); /* 0.4723665527410147turn */
}
div.box-3 {
  transform: rotate(calc(1turn * exp(-0.5))); /* 0.6065306597126334turn */
}
div.box-4 {
  transform: rotate(calc(1turn * exp(-0.25))); /* 0.7788007830714049turn */
}
div.box-5 {
  transform: rotate(calc(1turn * exp(0))); /* 1turn */
}

Result

Scale headings by fixed ratio

The exp() function can be useful for strategies like CSS modular scale, which relates all the font-sizes on a page to each other by a fixed ratio.

HTML

<h1>Heading 1</h1>
<h2>Heading 2</h2>
<h3>Heading 3</h3>
<h4>Heading 4</h4>
<h5>Heading 5</h5>
<h6>Heading 6</h6>

CSS

h1 {
  font-size: calc(1rem * exp(1.25)); /* 3.4903429574618414rem */
}
h2 {
  font-size: calc(1rem * exp(1)); /* 2.718281828459045rem */
}
h3 {
  font-size: calc(1rem * exp(0.75)); /* 2.117000016612675rem */
}
h4 {
  font-size: calc(1rem * exp(0.5)); /* 1.6487212707001282rem */
}
h5 {
  font-size: calc(1rem * exp(0.25)); /* 1.2840254166877414rem */
}
h6 {
  font-size: calc(1rem * exp(0)); /* 1rem */
}

Result

Specifications

Browser compatibility

See also

• pow()
• sqrt()
• hypot()
• log()