The National Motor Freight Traffic Association (NMFTA) created the National Motor Freight Classification (NMFC). It is used for all interstate, intrastate, and foreign commercial movement of LTL cargo. NMFC codes provide standardized freight classes to determine the transportability of the large variety of commodities that are shipped together in LTL shipments every year.
Adding NMFC code to a shipment is technically optional, but the NMFC codes can help avoid reclassification and ensure you're using the correct freight class number.
Multiply the length, width, and height of your shipment, then divide the total weight of your package by that number. If your shipment is 4 feet long, 5 feet wide, and 4 feet tall, you would multiply 4 x 5 x 4 to get 80 cubic feet. If it weighs 800 pounds, you would divide 800 / 80 to get 10 pounds per cubic foot.