Minecraft wiki entry for Measuring_distance, associated text: As you make something, e.g. a house, bigger in all directions, its surface area increases faster than its length, but not as fast as its volume. The surface area tells you how many blocks you'll need for the outer walls, but your interior furnishings probably increase according to the volume. Of course, shape matters: An 8×8×1 layer of dirt corresponds to a stack of 64 dirt blocks, but so does a 4×4×4 cube, or a 2×2×16 trench or shaft.