CYLINDER opening out showing equations for area of top and wall. The surface area of a cylinder is the area of the top and bottom plus the area of the wall. The area of the top is given by the formula for the area of a circle. So you need two of those (top + bottom). Then the area of the wall, which is the height (h) times the circumference (2?r). The volume of a cylinder is the area of the top times the height. This graphic shows the wall of the cylinder progressively opening out.