Logically, the surface area is the area of a given surface. There are several ways to interpret this in geometry: Area can mean the extent of the surface region on a two-dimensional plane. Surface area (often called the lateral surface area, although there is a difference) formulas for three-dimensional objects are more complex—all the surface areas are added around the outside of the object, from a cube to a sphere.

Surface area is commonly denoted as S for a surface in three dimensions, and A for the surface area of a two-dimensional plane (commonly, it is simply called “the area”). But be careful: The surface area of a three-dimensional object should not be confused with “volume”—or the total amount of space an object occupies. (For more about volume, see below.)