I don't know what type of packing materials you can get, or how you plan to ship, but keep in mind that UPS/FedEx charge by weight, not the size of the box. At least for smaller packages. Since bubble wrap and crumpled paper weigh basically nothing, it's never a bad idea to use a box that may be bigger than you need but gives you room for plenty of extra protection.
Are you sure, this doesnt make sense. They always measure my box and it would make sense box size matters as bigger boxes take up more space and shold cost more.
The above link is for Fedex Express shipments. Seems dimensional weight pricing won't hit Fedex ground until Jan 1 2015. http://ship.partnership.com/blog/bi...es-to-FedEx-Ground-Dimensional-Weight-Pricing
Good to know. I deal with UPS at work, and the only time dimensional weight comes into play is with large, light boxes. I'm sure that will change. If FedEx is doing it, UPS will do it.