A Freight Class Calculator is an online or offline tool that helps shippers find the correct freight class for their goods. Freight class is a number, usually between 50 and 500. This number tells the carrier how easy or difficult it is to ship your item. The calculator uses a few details about your shipment. These details include weight, length, width, height, density, value, and how easy the item is to handle. You enter this information, and the Freight Class Calculator gives you the right class.