What is freight class? The NMFC system explained

Freight class is the single biggest driver of your LTL rate — and the number shippers most often get wrong. Here’s what it is, how it’s set, and how to avoid a surprise reclass on your invoice.

What freight class actually is

Freight class is a standardized number, from 50 to 500, that carriers use to price less-than-truckload (LTL) shipments. It comes from the National Motor Freight Classification (NMFC), a system maintained by the NMFTA that assigns every commodity a class so any carrier can price it consistently. There are 18 classes: 50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400, and 500.

Lower class = denser, easier-to-handle freight = lower cost per pound. Higher class = light, bulky, fragile, or high-value freight = higher cost.

The four factors that set a class

• Density — pounds per cubic foot. This is the biggest factor for most freight.
• Stowability — how easily it loads with other freight (odd shapes, overlength, and hazmat are harder to stow).
• Handling — how much care it needs (fragile, awkward, or hard-to-lift items).
• Liability — value per pound, and how prone it is to theft or damage.

Many everyday commodities carry a fixed class in the NMFC regardless of density. For everything else, density decides the class.

How density sets your class

Density is your shipment’s total weight divided by its total cubic feet (length × width × height ÷ 1,728, times the number of pieces). The denser the freight, the lower the class:

Not sure of yours? The freight density calculator gives you cubic feet, density, and an estimated class in one step.

Why the wrong class costs you money

If you quote a lower class than your freight actually is, the carrier can reweigh and reclassit on the dock — then bill the difference, often with a correction fee. A class 70 shipment quoted as class 65, for example, can turn a clean quote into a higher invoice weeks later. Getting the class right up front keeps your quote and your invoice in agreement.