HugeNerd - 1:38 pm on Aug 12, 2008 (gmt 0)

I would say my level of explanation depends on the product and my description. Items which are necessarily large i.e. washing machines, should require no explanation. Some widgets are available in a variety of sizes; if properly differentiated in the product description, I don't think customers need to be told that a larger/heavier item may cost more to ship as a direct line item.

Personally, I think 98% of people have some point of reference for shipping costs -- nearly everyone has sent some sort of birthday or holiday gift box. The biggest bit of input people might lack is the origination of the shipment; they'll expect higher shipping costs if they know they live 3,000 miles away!