Freight class matters because it directly controls how much you pay for shipping. Two shipments with the same weight can have very different costs if their freight classes are different. This often surprises new shippers, but it is a normal part of freight pricing. The main reason freight class matters is risk and efficiency. Carriers want to know how much space your shipment takes, how easy it is to move, and how likely it is to be damaged. A higher freight class means more risk or more space used, which increases costs for the carrier.