Subclasses for
Almost all U.S. LTL carriers use NMFC freight classes, although some are attempting to move to a dimensionally-based system.
If the couch you are shipping has not been assembled yet and you are shipping various components that you can use freight class 250. If you are shipping a complete product then you should use freight class 175.
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.