The width CSS property sets an element's width. By default, it sets the width of the content area, but if box-sizing is set to border-box, it sets the width of the border area.

The min-width and max-width properties override width.


/* <length> values */
width: 300px;
width: 25em;

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

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

/* Global values */
width: inherit;
width: initial;
width: revert;
width: unset;


Defines the width as an absolute value.
Defines the width as a percentage of the containing block's width.
The browser will calculate and select a width for the specified element.
The intrinsic preferred width.
The intrinsic minimum width.
Uses the fit-content formula with the available space replaced by the specified argument, i.e. min(max-content, max(min-content, <length-percentage>)).

Accessibility concerns

Ensure that elements set with a width aren't truncated and/or don't obscure other content when the page is zoomed to increase text size.

Formal definition

Initial valueauto
Applies toall elements but non-replaced inline elements, table rows, and row groups
Percentagesrefer to the width of the containing block
Computed valuea percentage or auto or the absolute length
Animation typea length, percentage or calc();

Formal syntax

auto | <length> | <percentage> | min-content | max-content | fit-content | fit-content(<length-percentage>)

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


Default width

p.goldie {
  background: gold;
<p class="goldie">The Mozilla community produces a lot of great software.</p>

Pixels and ems

.px_length {
  width: 200px;
  background-color: red;
  color: white;
  border: 1px solid black;

.em_length {
  width: 20em;
  background-color: white;
  color: red;
  border: 1px solid black;
<div class="px_length">Width measured in px</div>
<div class="em_length">Width measured in em</div>


.percent {
  width: 20%;
  background-color: silver;
  border: 1px solid red;
<div class="percent">Width in percentage</div>


p.maxgreen {
  background: lightgreen;
  width: intrinsic;           /* Safari/WebKit uses a non-standard name */
  width: -moz-max-content;    /* Firefox/Gecko */
  width: -webkit-max-content; /* Chrome */
  width: max-content;
<p class="maxgreen">The Mozilla community produces a lot of great software.</p>


p.minblue {
  background: lightblue;
  width: -moz-min-content;    /* Firefox */
  width: -webkit-min-content; /* Chrome */
  width: min-content;
<p class="minblue">The Mozilla community produces a lot of great software.</p>


Specification Status Comment
CSS Box Sizing Module Level 4
The definition of 'width' in that specification.
Editor's Draft
CSS Box Sizing Module Level 3
The definition of 'width' in that specification.
Working Draft Added the max-content, min-content, fit-content keywords.
CSS Level 2 (Revision 1)
The definition of 'width' in that specification.
Recommendation Precises on which element it applies to.
CSS Level 1
The definition of 'width' in that specification.
Recommendation Initial definition.

Browser compatibility

BCD tables only load in the browser

See also