exp()

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 {{CSSxRef("pow", "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 {{CSSxRef("number")}}. Representing the value to be raised by a power of e.

Return value

Returns a non-negative {{CSSxRef("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

{{CSSSyntax}}

Examples

Rotate elements

The exp() function can be used to {{CSSxRef("transform-function/rotate", "rotate")}} elements as it return a {{CSSxRef("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

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(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

{{EmbedLiveSample('Rotate elements', '100%', '200px')}}

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

{{EmbedLiveSample('Scale headings by fixed ratio', '100%', '300px')}}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{CSSxRef("pow")}}
• {{CSSxRef("sqrt")}}
• {{CSSxRef("hypot")}}
• {{CSSxRef("log")}}