Minecraft wiki entry for Mapping, associated text: Following the Pretty Scary Update, zoom-level 0 maps will not overlap—they are created with each center 128 blocks from each other center. Since the center-most map has an origin of 0,y,0, each zoom-level 0 map has an x-coordinate and z-coordinate which are each a multiple of 128. All maps created within 64 blocks of a particular pre-defined center will be identical.