Typically boxes for frames need to be +/- 8" wide, 22+" tall, and around 40-45" long, depending on the size of the frame. In order to calculate the size, you double the two shortest dimensions, and add the longest. Using a 8" wide box (typical bike box), 41" in length, 24" tall gives a total of 107" and allows room for padding and such.
I live in fear every time I buy a bike from a seller with no clue about packing and shipping bikes/frames, even though I try to tell them (nicely) it needs to be secured inside the box and protected from crush and impact. I've received more than a couple just tossed in a box-the last one I bought arrived with a beautiful M900 rear derailleur sticking outside the box, a bent derailleur hanger, and nasty scratches.
It really matters where they put the label (needs to be on top) and they should write 'Please do not lay flat' in large letters on all sides of the box. If it gets laid down, the frame is not going to be happy no matter how far the journey.