Understanding Freight Classes and NMFC Codes

What Are Freight Classes?

Freight classes are a standardized classification system created by the National Motor Freight Traffic Association (NMFTA) to categorize commodities shipped via less-than-truckload (LTL) carriers. The system assigns each type of commodity a class number ranging from 50 to 500, which directly influences the shipping rate a carrier charges. Understanding freight classes is essential for anyone involved in trucking and logistics because incorrect classification can lead to reclassification fees, billing disputes, and unexpected costs.

The 18 Freight Classes

There are 18 possible freight classes: 50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400, and 500. Class 50 represents the lowest-cost, easiest-to-ship freight, while Class 500 represents the most expensive and difficult-to-handle commodities.

How Freight Classification Works

NMFTA evaluates four primary characteristics when assigning a freight class:

• Density: The weight per cubic foot of the commodity. Denser freight generally receives a lower (cheaper) class because it uses trailer space more efficiently.
• Stowability: How easily the freight can be arranged alongside other shipments. Irregularly shaped items or hazardous materials are harder to stow and receive higher classes.
• Handling: The level of care, equipment, or labor required to load and unload the freight. Fragile or heavy items that need special equipment cost more to handle.
• Liability: The risk of damage, theft, or spoilage. Perishable goods and high-value items carry greater liability and higher classes.

What Are NMFC Codes?

The National Motor Freight Classification (NMFC) system assigns a unique numeric code to every commodity type. Each NMFC code maps to a specific freight class. For example, machinery parts might fall under NMFC code 123450 with a freight class of 85, while lightweight plastic goods might be assigned NMFC code 156780 with a class of 150.

Carriers, shippers, and brokers use NMFC codes on bills of lading to ensure everyone agrees on the classification and resulting rate. The NMFTA publishes and regularly updates the official NMFC tariff, which contains thousands of commodity listings.

Sub-classifications and Density-Based Classes

Many NMFC codes include sub-classifications that refine the class based on packaging, density, or other factors. A growing number of commodities are now classified under density-based rules, where the freight class is determined entirely by the shipment''s actual density rather than a fixed assignment. Carriers often require detailed dimensions and weight to calculate density-based classifications accurately.

Why Accurate Classification Matters

Misclassifying freight can have significant financial consequences:

1. Reclassification charges: If a carrier inspects freight and finds the actual class differs from what was declared, they will reclassify it and issue an adjusted invoice, often with an inspection fee.
2. Billing disputes: Incorrect NMFC codes lead to back-and-forth disputes between shippers, carriers, and brokers that waste time and damage relationships.
3. Higher costs: Consistently under-classifying freight may result in carriers auditing your shipments more frequently or adjusting your rate agreements.

Best Practices for Carriers and Shippers

• Always verify the NMFC code before filling out the bill of lading
• Measure and weigh shipments accurately to support density-based classifications
• Keep a copy of the current NMFC tariff or use the NMFTA''s online ClassIT tool
• When in doubt, consult with your carrier or freight broker before shipping
• Review accessorial charges that may apply based on commodity type

Carriers can verify their operating authority and compliance status through our authority lookup to ensure they are properly set up to handle the freight classes they transport.