CSS3 box-sizing Property


Specify two bordered boxes side by side:

div {
    box-sizing: border-box;
    width: 50%;
    float: left;

Try it yourself »

Definition and Usage

The box-sizing property is used to tell the browser what the sizing properties (width and height) should include.

Should they include the border-box or just the content-box which is the default value of the width and height properties.

For example, if you want two bordered boxes side by side, it can be achieved through setting box-sizing to "border-box". This forces the browser to render the box with the specified width and height, and place the border and padding inside the box.

Default value: content-box
Inherited: no
Animatable: no. Read about animatable
Version: CSS3
JavaScript syntax: object.style.boxSizing="border-box" Try it

Browser Support

The numbers in the table specify the first browser version that fully supports the property.

Numbers followed by -webkit- or -moz- specify the first version that worked with a prefix.

box-sizing 10.0
4.0 -webkit-
8.0 29.0
2.0 -moz-
3.2 -webkit-

CSS Syntax

box-sizing: content-box|border-box|initial|inherit;

Property Values

Value Description
content-box Default. The width and height properties (and min/max properties) includes only the content. Border, padding, or margin are not included
border-box The width and height properties (and min/max properties) includes content, padding and border, but not the margin
initial Sets this property to its default value. Read about initial
inherit Inherits this property from its parent element. Read about inherit

Related Pages

CSS3 tutorial: CSS3 User Interface

HTML DOM reference: boxSizing property


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