Triangular Pyramid Surface Area Calculator Find the surface area of a pyramid with a triangular base with this Pyramid Surface Area Calculator. Base Perimeter: To find the perimeter of a triangle use: Triangle Perimeter Calculator Base Area: To find the area of the triangular base use: Triangle Area Calculator Slant Length: This is the distance from the center of the base on oneof the lateral surface triangles, to the tip of that surface triangle. Fill in the perimeter and area of the triangular base of a regular pyramid, and the height of the regular pyramid to determine surface area.