With a Boston courier service, a freight class will be assigned to anything you are shipping. Basically, these companies use the freight class as a system for figuring what they will charge you for shipping a particular item. Couriers have various formulas they will use to calculate shipping rates, and the freight class is a major part of it. There are several other figures that are included in the formula as well, including distance, mileage, special requirements, such as lift gates, storage fees, taxes, surcharges, and any other charges or fees that might apply. The final shipping cost that shows up on your invoice is a combination of all of these things, and probably more. Now it's not so surprising to see how expensive it is to ship certain things.
The size and weight of the item you are shipping are the two determining factors for what freight class your item will end up in. These two factors will affect many different areas of the shipping process. For example, it will decide how many other items can be placed in the truck with it, if anything. It may require a separate truck just to ship a single item. In this case, the weight is still important when considering the gas mileage of the truck. If your item is the only one able to be carried in a single truck, you may be charged differently than if it were in with items from other clients. It's important for couriers to make sure every run they make is productive, so you may get charged more if your item is taking up a lot of space that could be used by someone else. This is why the freight class is so important for calculating shipping charges.
The freight class for your particular item may change as well when it becomes apparent that it will be somewhat more difficult to ship than other items. An example of this would be if a crane is required to lift the item. Obviously, this would take more time, and possibly more man power than just throwing a few boxes in the back of a van. The freight class is the most effective system for establishing fair shipping rates. This same system would probably apply when you deal with one of the many Boston airport couriers as well. It's nice to know that the prices they throw out there are not just random.