What is a freight class?

Learn what a freight class is and what resources you can use to identify the freight classes of your products.

Freight class is a measure of cubic volume used in conjunction with weight to identify how much of a semi-trailer will be needed to accommodate a shipment. Freight class and weight are required to obtain LTL freight rate estimates.

50 is the lowest freight class and is reserved for the densest commodities. 500 is the highest freight class and is reserved for the least dense commodities. 200 pounds of a commodity with a freight class of 50 will be significantly smaller in size than one with a freight class of 500 weighing the same amount. The price charged per pound of freight will increase as the freight class increases since commodities with higher freight classes will consume more of the semi-trailer, leaving less space available for other shipments.

In all, there are four traits that determine the freight class of a commodity:

  • Density
  • Handling
  • Stowability
  • Liability

To get a more in-depth understanding of freight classes, refer to our blog post titled, Freight Class for Ecommerce 101.

A shipment's freight class is identified by the shipper during the shipment preparation process. Carriers routinely audit the freight class and will correct it if they believe it is incorrect, a practice referred to as reclassing. Reclassing a shipment can have a significant impact on the associated charges, and therefore it is very important to make sure that the freight class of your products is accurately identified.

The official resource for identifying a commodity's freight class is the National Motor Freight Classification (NMFC) directory maintained by the National Motor Freight Transportation Agency (NMFTA.org). You can purchase a hard copy of the directory or obtain an online subscription to it from their web site.

Other resources for discovering the freight classes of your products include:

  1. Carrier invoices. They typically document the freight class used to determine charges for a shipment.
  2. The personnel in the shipping department. If they are experienced they will know the freight class of the products they ship.
  3. The carrier's customer service department. You will need to give them detailed descriptions of the products you will be shipping.
  4. Freight class calculators found online.  You can use our blog post, Freight Class Calculators From 23 LTL Carriers, to access the freight class calculators from many of the carriers we publish applications for.

Doing your own online search for freight class calculator will return many options. Use the calculator offered by the carrier you intend to use if one is available. Using a calculator from another carrier or resource may return a different result than what your carrier will use for billing purposes if the commodity is on the threshold of two freight classes (i.e. 65 vs 70). Examine your freight invoices when received to confirm the freight class you are using. Using a freight class that is inconsistent with your carrier's determination will result in a difference between the quoted and billed rate.

Companies tend to sell products that can be grouped into just a few freight classes.