height CSS property

Try it

height: 150px;

height: 6em;

height: 75%;

height: auto;

<section class="default-example" id="default-example">
  <div class="transition-all" id="example-element">
    This is a box where you can change the height.
  </div>
</section>

#example-element {
  display: flex;
  flex-direction: column;
  background-color: #5b6dcd;
  justify-content: center;
  color: white;
}

Syntax

/* <length> values */
height: 120px;
height: 10em;
height: 100vh;
height: anchor-size(height);
height: anchor-size(--my-anchor self-block, 250px);
height: clamp(200px, anchor-size(width));

/* <percentage> value */
height: 75%;

/* Keyword values */
height: max-content;
height: min-content;
height: fit-content;
height: fit-content(20em);
height: auto;
height: stretch;

/* Global values */
height: inherit;
height: initial;
height: revert;
height: revert-layer;
height: unset;

Values

<length>

Defines the height as a distance value.

<percentage>

Defines the height as a percentage of the containing block's height.

auto

The browser will calculate and select a height for the specified element.

max-content

The intrinsic preferred height.

min-content

The intrinsic minimum height.

fit-content

Use the available space, but not more than max-content, i.e., min(max-content, max(min-content, stretch)).

fit-content(<length-percentage>)

Uses the fit-content formula with the available space replaced by the specified argument, i.e., min(max-content, max(min-content, <length-percentage>)).

stretch

Sets the height of the element's margin box to the height of its containing block. It attempts to make the margin box fill the available space in the containing block, so in a way behaving similar to 100% but applying the resulting size to the margin box rather than the box determined by box-sizing.

Accessibility

• MDN Understanding WCAG, Guideline 1.4 explanations
• Understanding Success Criterion 1.4.4 | W3C Understanding WCAG 2.0​ (external)

Formal definition

Formal syntax

height = 
  auto                                      |
  <length-percentage [0,∞]>                 |
  min-content                               |
  max-content                               |
  fit-content( <length-percentage [0,∞]> )  |
  <calc-size()>                             |
  <anchor-size()>                           |
  stretch                                   |
  fit-content                               |
  contain                                   

<length-percentage> = 
  <length>      |
  <percentage>  

<calc-size()> = 
  calc-size( <calc-size-basis> , <calc-sum> )  

<anchor-size()> = 
  anchor-size( [ <anchor-name> || <anchor-size> ]? , <length-percentage>? )  

<calc-size-basis> = 
  <size-keyword>  |
  <calc-size()>   |
  any             |
  <calc-sum>      

<calc-sum> = 
  <calc-product> [ [ '+' | '-' ] <calc-product> ]*  

<anchor-name> = 
  <dashed-ident>  

<anchor-size> = 
  width        |
  height       |
  block        |
  inline       |
  self-block   |
  self-inline  

<calc-product> = 
  <calc-value> [ [ '*' | / ] <calc-value> ]*  

<calc-value> = 
  <number>        |
  <dimension>     |
  <percentage>    |
  <calc-keyword>  |
  ( <calc-sum> )  

<calc-keyword> = 
  e          |
  pi         |
  infinity   |
  -infinity  |
  NaN        

Examples

Setting height using pixels and percentages

HTML

<div id="taller">I'm 50 pixels tall.</div>
<div id="shorter">I'm 25 pixels tall.</div>
<div id="parent">
  <div id="child">I'm half the height of my parent.</div>
</div>

CSS

div {
  width: 250px;
  margin-bottom: 5px;
  border: 2px solid blue;
}

#taller {
  height: 50px;
}

#shorter {
  height: 25px;
}

#parent {
  height: 100px;
}

#child {
  height: 50%;
  width: 75%;
}

Result

Stretch height to fill the containing block

HTML

<div class="parent">
  <div class="child">text</div>
</div>

<div class="parent">
  <div class="child stretch">stretch</div>
</div>

CSS

@supports not (height: stretch) {
  body::before {
    content: "Your browser doesn't support the `stretch` value yet.";
    background-color: wheat;
    display: block;
    text-align: center;
    padding: 1rem 0;
  }
}

.parent {
  height: 150px;
  margin: 1rem;
  border: solid;
}

.child {
  margin: 1rem;
  background: #00999999;
}

.stretch {
  height: stretch;
}

Result

Specifications

Browser compatibility

See also

• width
• box-sizing
• min-height, max-height
• block-size, inline-size
• anchor-size()
• clamp()
• minmax()
• SVG height attribute
• Introduction to the CSS box model
• CSS box model module