Posted July 18, 200817 yr Optimal box internal volume is 1.1 after displacement, therefore, before displacement it would be 1.1 + .14 = 1.24 cubic feet.Would it be more advisable to buy a box that is slightly bigger than 1.24 and put something inside of it to displace volume or to buy a box slightly smaller and fill with polyfill? I'm finding boxes with 1.0 cubic feet and 1.5 and not sure which way to go.