Definition
Freight class is the standardized classification system for LTL (less-than-truckload) shipments, established by the National Motor Freight Traffic Association (NMFTA). There are 18 freight classes ranging from Class 50 (densest, cheapest) to Class 500 (least dense, most expensive). A freight class is determined by four characteristics: density (pounds per cubic foot), stowability (ease of stacking and loading), handling difficulty, and liability (risk of damage or theft). Class 50 covers dense items like steel or bricks; Class 500 covers very light or bulky items like styrofoam. LTL carriers calculate freight charges by multiplying the base rate by a class-specific factor.
Why It Matters
Incorrect freight class is one of the most common and expensive LTL billing errors. If your stated class is lower than what the carrier determines upon reweigh and inspection, you receive a reclassification invoice — often 30–60% more than the original quote. Distributors managing regular LTL shipments should audit their freight class assignments by commodity and update them when density or stowability changes. Freight Rate Calculator →
Frequently Asked Questions
How is freight class determined?
Freight class is determined by four factors: density (primary driver — higher density = lower class = lower rate), stowability (can it be stacked or loaded efficiently?), handling difficulty (fragile, hazardous, or irregular shape adds class), and liability (value and theft risk). NMFTA publishes the National Motor Freight Classification (NMFC) standards.
What is the lowest and highest freight class?
Class 50 is the lowest (densest, cheapest) — typically applies to heavy, dense commodities like steel, stone, or heavy machinery parts. Class 500 is the highest (least dense, most expensive) — typically applies to very light or bulky items like ping pong balls, assembled furniture, or matresses.
How do I find the freight class for my product?
You can determine freight class using the NMFTA NMFC lookup (by commodity description) or by calculating density: weight / volume in cubic feet, then cross-reference the NMFC class table. Your LTL carrier can also provide class guidance, though they may classify differently on inspection.