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The width CSS property specifies the width of an element. By default, the property defines the width of the content area. If box-sizing is set to border-box, however, it instead determines the width of the border area.

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

Syntax

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

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

/* Keyword values */
width: 25em border-box;
width: 75% content-box;
width: max-content;
width: min-content;
width: available;
width: fit-content;
width: auto;

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

The width property is specified as either:

Values

<length>
Defines the width as an absolute value.
<percentage>
Defines the width as a percentage of the containing block's width. If the width of the containing block depends on the width of the element, the resulting layout is undefined.
border-box
If present, the preceding <length> or <percentage> is applied to the element's border box.
content-box
If present, the preceding <length> or <percentage> is applied to the element's content box.
auto
The browser will calculate and select a width for the specified element.
fill
Use the fill-available inline size or fill-available block size, as appropriate to the writing mode.
max-content
The intrinsic preferred width.
min-content
The intrinsic minimum width.
available
The containing block width minus horizontal margin, border and padding.
fit-content
The larger of:
  • the intrinsic minimum width
  • the smaller of the intrinsic preferred width and the available width

Formal syntax

[ <length> | <percentage> ] && [ border-box | content-box ]? | available | min-content | max-content | fit-content | auto

Examples

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>

Percentage

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

max-content

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

min-content

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

Accessibility concerns

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

Specifications

Specification Status Comment
CSS Basic Box Model
The definition of 'width' in that specification.
Working Draft Added the max-content, min-content, available, fit-content, border-box, content-box keywords.
CSS Transitions
The definition of 'width' in that specification.
Working Draft Lists width as animatable.
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.
CSS Intrinsic & Extrinsic Sizing Module Level 3
The definition of 'width' in that specification.
Working Draft Adds new sizing keywords for width and height.
Initial valueauto
Applies toall elements but non-replaced inline elements, table rows, and row groups
Inheritedno
Percentagesrefer to the width of the containing block
Mediavisual
Computed valuea percentage or auto or the absolute length
Animation typea length, percentage or calc();
Canonical orderthe length or percentage before the keyword, if both are present

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes12143.51
Animatable ? ?16 ? ? ?
max-content

46

22 -webkit-

No3 -moz- ?15 -webkit-

6.1 -webkit-

21

min-content

46

222

No3 -moz- ?15 -webkit-

6.1 -webkit-

22

available No No3 -moz- ? ? ?
fill-available22 -webkit- No No ? ?6.1 -webkit-
fit-content

46

22 -webkit-

No3 -moz- No15 -webkit- 6.1 -webkit-
content-box No No No No No No
border-box No No No No No No
fill46 No ? ? ? ?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes4 Yes Yes Yes
Animatable ? ? ?16 ? ? ?
max-content4646 No ? ? ?5.0
min-content4646 No ? ? ?5.0
available ? ? No ? ? ? No
fill-available4646 No ? ? ?5.0
fit-content4646 No ? ? ?5.0
content-box ? ? No ? ? ? No
border-box ? ? No ? ? ? No
fill4646 No ? ? ?5.0

1. Supported as intrinsic.

2. Supported as min-intrinsic.

See also