High Quality Content by WIKIPEDIA articles! The surface-area-to-volume ratio also called the surface-to-volume ratio and variously denoted sa/vol or SA:V, is the amount of surface area per unit volume of an object or collection of objects. The surface area to volume ratio is measured in units of inverse distance. A cube with sides of length a will have a surface area of 6a2 and a volume of a3. The surface to volume ratio for a cube is thus 6/a. For a given shape, SA:V decreases linearly with increasing size. A cube 2 m on a side has a ratio of 3 m?1, half that of a cube 1 m on a side. Conversely, preserving SA:V as size increases requires changing to a less compact shape.