Home Course CSS Box Model

CSS Box Model

by MH RISHAD - 03 Oct 2020

Box Model of CSS

HTML elements are considered boxes. "Box model" is used when talking about design and layout.

CSS box model is essentially a box that wraps around in every HTML element.

It consists of:

“margins, borders, padding, and the actual content”

The image below illustrates the box model:



Details Different parts of:

  • Content - The content of the box, where text and images appear
  • Padding - Clears an area around the content. The padding is transparent
  • Border - A border that goes around the padding and content
  • Margin - Clears an area outside the border. The margin is transparent

The box model allows us to add a border around elements




div {

  width: 500px;

  border: 10px solid red;

  padding: 40px;

  margin: 25px;



Width and Height

In order to set the width and height of an element correctly in all browsers, you need to know how the box model works.


Note: The width and height properties of an element with CSS, just set the width and height of the content area. Calculate the full size of an element, you must also add padding, borders and margins.


This <div> element will have a total width of 250px:


div {

  width: 204px;

  padding: 15px;

  border: 8px solid #999;

  margin: 0px;


Here is the calculation:

204px (width)

+ 15px (left + right padding)

+ 8px (left + right border)

+ 0px (left + right margin)

= 250px


The total width of an element should be calculated like this:

Total element width = width + left padding + right padding + left border + right border + left margin + right margin

The total height of an element should be calculated like this:

Total element height = height + top padding + bottom padding + top border + bottom border + top margin + bottom margin


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