width

Summary

The width CSS property specifies the width of the content area of an element. The content area is inside the padding, border, and margin of the element.

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

• Initial value auto
• Applies to all elements but non-replaced inline elements, table rows, and row groups
• Inherited no
• Percentages refer to the width of the containing block
• Media visual
• Computed value the percentage or auto as specified or the absolute length
• Animatable yes, as a length, percentage or calc(); when both values are lengths, they are interpolated as lengths; when both values are percentages, they are interpolated as percentages; otherwise, both values are converted into a calc() function that is the sum of a length and a percentage (each possibly zero), and these calc() functions have each half interpolated as real numbers.
• Canonical order the length or percentage before the keyword, if both are present

Syntax

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

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

width: 75%          /* <percentage> values */

width: border-box   /* Keyword values */
width: content-box
width: max-content
width: min-content
width: available
width: fit-content
width: auto

width: inherit

Values

<length>

See <length> for possible units.

<percentage>

Specified as a <percentage> of containing block's width.

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.

max-content

The intrinsic preferred width.

min-content

The intrinsic minimum width.

available

The containing block width minus horizontal margin, border and padding.

Note: WebKit implements a variation of this value, under the name fill-available as of December 2013.

fit-content

The larger of:

• the intrinsic minimum width
• the smaller of the intrinsic preferred width and the available width

Note: WebKit implements an earlier version of this value, under the name intrinsic, but as of June 2012, implements fit-content as well.

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>

Specifications

Browser compatibility

See also

• box model, height, box-sizing, min-width, max-width