The size of the padding, border, and margin all increase the amount of space on a web page that an element occupies or influences. However, the dimensions of these properties are generally not included in the calculated width or height of an element.  Please explain how you calculate box size.

What will be an ideal response?

By default, when you specify dimensions for an element using thewidthandheightproperties, the values you specify apply only to the element content. Any values you specify for padding, border, or margin are added to the height or width value you specify. Especially when you're fitting an element into a limited amount of space, you need to subtract the additional area occupied by padding, border, and margin to arrive at the appropriate width or height value. For instance, when the width of an element must fit into a limited space, you have to subtract both the left and right values for padding, border, and margin to arrive at the appropriate width value for your style sheet. Similarly, to calculate a height value, you need to subtract all three values for the top and bottom of the element.