Have you ever shipped a large box that seems to weigh nothing, yet the invoice you get is higher than you expected? This likely has to do with the difference between dimensional weight and actual weight. We all know how to find the actual weight of our international packages; we just look at the scale the box is sitting on and read the number. But why does my 10 lb shipment in a 12x12x12 inch box cost less than those same 10 lbs in a 24x24x24 inch box?