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.
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.