A Freight Class calculator is an online tool that helps you find the correct freight class for your shipment. Freight class is a number between 50 and 500. Lower numbers usually mean lower shipping costs, while higher numbers mean higher costs. The calculator uses shipment details like weight, length, width, and height to calculate density. Density is the most important part of freight class calculation. The reason this calculator is so important is simple. If you choose the wrong freight class, the carrier may reclassify your shipment later. This can lead to extra charges, delays, or even rejected shipments. A Freight Class calculator reduces these risks by giving you an accurate estimate before shipping.