CSS width

The CSS width property is used to specify the width of an element.

More specifically, the width property sets the width of the content area or border area (depending on the value of the box-sizing property) of certain boxes.

You can use a length or percentage to specify the width, or you can use one of the keywords.

Also see the max-width, height, and max-height properties.

Syntax

Possible Values

auto: The width depends on the values of other properties. The browser will calculate the width accordingly.
length: Specifies a length value for the width (for example 300px). Negative values are illegal.
percentage: Specifies a percentage value for the width (for example 80%). This is calculated as a width of the generated box's containing block. Negative values are illegal.
min-content: The intrinsic minimum width of the content.
max-content: The intrinsic preferred width of the content.
fit-content(length-percentage): Uses the fit-content formula with the available space replaced by the specified argument.
stretch: Expands the element's width to fill the available space of its containing block.

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial: Represents the value specified as the property's initial value.
inherit: Represents the computed value of the property on the element's parent.
unset: This value acts as either inherit or initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.

General Information

Initial Value: auto
Applies To: All except for table rows, row groups, and non-replaced inline elements.
Inherited?: No
Media: Visual
Animatable: Yes (see example)

Example Code

Here are some examples of valid widths:

Official Specifications

CSS Box Sizing Module Level 3 (W3C Editor's Draft)
CSS Box Sizing Module Level 3 (W3C Working Draft)
CSS Level 2.1 (W3C Recommendation 07 June 2011)
CSS Level 1 (W3C Recommendation 17 Dec 1996)

Browser Support

Browser support for CSS properties can vary, particularly for newer or experimental features. Check current browser compatibility before using a property in production, especially when supporting older browsers.

Initial Value

CSS properties have an initial value that applies when the property has not been explicitly set. The initial value is different from the value inherited from a parent element and may vary between properties.

Inheritance

Some CSS properties inherit their computed value from their parent element by default, while others do not. The inherit, initial, unset, and revert keywords can also be used to control how a property gets its value.

Vendor Prefixes

Most modern CSS properties use the standard, unprefixed syntax. Vendor-prefixed properties such as -webkit- are mainly relevant to older browser versions or specific features and should only be used when required by your browser support targets.