Almost all U.S. LTL carriers use NMFC freight classes, although some are attempting to move to a dimensionally-based system.

The first step in determining your freight class is to take measurements. Measure the height, width and depth of your shipment then multiple those three measurements together for the total cubic feet. Then divide the total cubic inches by 1,728 (the number of cubic inches in a cubic foot). Finally, divide the weight (in pounds) of the shipment by the total cubic feet.

NMFC freight subclasses are used to differentiate among commodities of the same type. For example, one NMFC code for chairs/stools is 82790. Subclasses 82790-1 and 82790-11, despite have the same base NMFC code, fall into two different freight classes.