The National Motor Freight Traffic Association (NMFTA) annually publishes a list of freight class designations, codes, and subclasses for commonly shipped items (https://classit.nmfta.org/). To access this list, you are required to pay a subscription fee. Learn more about freight classes for free on our freight classes pages.
Freight Class 500 freight is the most expensive to ship. This classification is reserved for items of very high value or for items that use lots of space but weigh very little.
No. While density is one of the primary factors in determining NMFC freight class, other factors, such as value, are also used in making that determination. Gold bars, for example, are very dense, but they fall into shipping class 500 along with very low-density items because of their high value.