CSS Box Sizing Property

Box-sizing property is used to change the height and width of the element. Since CSS2, the box property has worked like as shown below −

width + padding + border = actual visible/rendered width of an element's box
height + padding + border = actual visible/rendered height of an element's box


To understand the box-sizing property, let us see an example:

Live Demo

         .div1 {
            width: 300px;
            height: 100px;
            border: 1px solid blue;
            box-sizing: border-box;
         .div2 {
            width: 300px;
            height: 100px;
            padding: 50px;
            border: 1px solid red;
            box-sizing: border-box;
      <div class = "div1">TutorialsPoint.com</div></br>
      <div class = "div2">TutorialsPoint.com</div>