National Motor Freight Classification (NMFC) is a freight classification system created by the National Motor Freight Traffic Association (NMFTA) and used for interstate, intrastate, and foreign commerce shipping of LTL cargo. NMFC freight codes provide standardized freight classes to determine the ease of transport of many of the huge variety of different commodities being shipped together in LTL shipments every year.

Every commodity has both a freight class and a NMFC code. Freight class represents a category of items while NMFC codes relate to specific commodities within each of the 18 freight classes.

NOI stands for Not Otherwise Indicated. This is used when a commodity does not have an NMFC code. In these cases, density is usually used to determine freight class.