The max-height CSS property sets the maximum height of an element. It prevents the used value of the height property from becoming larger than the value specified for max-height.

Try it

max-height: 150px;

max-height: 7em;

max-height: 75%;

max-height: 10px;

<section class="default-example" id="default-example">
  <div class="transition-all" id="example-element">
    This is a box where you can change the maximum height. <br />This will limit
    how tall the box can be, potentially causing an overflow.
  </div>
</section>

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

max-height overrides height, but min-height overrides max-height.

Syntax

/* <length> value */
max-height: 3.5em;
max-height: anchor-size(height);
max-height: calc(anchor-size(--my-anchor self-block, 250px) + 2em);

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

/* Keyword values */
max-height: none;
max-height: max-content;
max-height: min-content;
max-height: fit-content;
max-height: fit-content(20em);
max-height: stretch;

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

Values

<length>

Defines the max-height as an absolute value.

<percentage>

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

none

No limit on the size of the box.

max-content

The intrinsic preferred max-height.

min-content

The intrinsic minimum max-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, argument)).

stretch

Limits the maximum 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.

Note: To check aliases used by browsers for the stretch value and its implementation status, see the Browser compatibility section.

Accessibility

Ensure that elements set with a max-height are not truncated and/or do not obscure other content when the page is zoomed to increase text size.

• MDN Understanding WCAG, Guideline 1.4 explanations
• Understanding Success Criterion 1.4.4 | W3C Understanding WCAG 2.0

Formal definition

Formal syntax

max-height = 
  none                                      |
  <length-percentage [0,∞]>                 |
  min-content                               |
  max-content                               |
  fit-content( <length-percentage [0,∞]> )  |
  <calc-size()>                             |
  <anchor-size()>                           

<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 max-height using percentage and keyword values

table {
  max-height: 75%;
}

form {
  max-height: none;
}

Specifications

Browser compatibility

See also

• min-height
• height
• max-inline-size
• max-block-size
• box-sizing
• Introduction to the CSS box model guide
• CSS box model module