The National Motor Freight Classification, also known as the freight class number, of a commodity is typically assigned by a shipping company. It is a standard in international shipping created by the National Motor Freight Traffic Association, designed to determine the transportability of a specific shipment.
There are 18 freight classes in the NMFC system, ranging in values from 50 to 500; the lower the number is in the system, the cheaper and easier it is to transport. Factors that determine this value include: length, height, weight, density, ease of handling and value. Durable items that are well-packaged and can fit on a standard 4 foot by 4 foot pallet are assigned low classes and include construction materials, car parts and books. Large or easily breakable items with little density, as well as valuable items, are at the high end and include examples like bags of gold dust, ping pong balls and wooden furniture.