To establish fair measures and standardize freight pricing, the National Motor Freight Traffic Association (NMFTA) created a freight classification system for all types of commodities. This structure, featuring well-defined classes, is the National Motor Freight Classification system, commonly referred to as NMFC.

Commodities are grouped into 18 freight classes between 50 and 500. NMFC codes specifically relate to unique commodities within each of the 18 freight classes. Shippers and carriers commonly use these freight classifications as a common standard when setting shipping rates.

Characteristics of NMFC freight classifications
NMFC codes are based on four characteristics:

Freight density
Freight stowability
Ease of handling
Liability