Freight class has a direct impact on how much you pay for shipping. Many new shippers think weight alone decides price. But in freight shipping, class is just as important, sometimes even more important. Freight class is based on four main factors. These are density, stowability, handling, and liability. Density means how heavy your item is compared to its size. A small heavy box has high density. A large light box has low density. Low-density items usually have higher freight classes and cost more to ship. A Freight Class Calculator considers these factors, especially density. When you enter dimensions and weight, it calculates density and suggests a class. This helps you see how changing packaging can change cost.