The height of the shipping box is the same as the height of the boxes that are about to be shipped. (4 1/2 inches). So you can get 1 layer of the boxes to be shipped.
The length of the shipping box is 18 inches. You will be able to get 18/4.5 = 4 boxes along the 18 inch side.
The 9 inch side will allow 2 boxes.
In all you can ship 2 * 4 boxes in the shipping box which is eight 4 1/2 inch cubes in all.
