Less-than-truckload rates are driven heavily by freight class — a standardized system (NMFC, the National Motor Freight Classification) that groups commodities into 18 classes from 50 to 500 based on density, handling, stowability, and liability.
Density Is the Biggest Factor
Lower-density items (bulky, lightweight) generally carry a higher class — and a higher rate per hundredweight — because they take up trailer space without contributing much weight. Denser, more compact freight typically qualifies for a lower class and a better rate.
Why Misclassification Costs Money Both Ways
Under-declaring your freight class to get a lower rate is a common shortcut that backfires: carriers can and do reweigh and reclass shipments, and reclassification fees plus a corrected invoice usually cost more than getting it right the first time. Over-declaring, on the other hand, means paying more than you need to on every single shipment.
How to Get Your Class Right
- Calculate actual density (weight divided by cubic footage) rather than estimating
- Check the current NMFC item number for your specific commodity rather than assuming based on a similar product
- Reverify class when packaging changes — a new box size changes your density calculation
- Keep documentation of your density calculation in case a carrier disputes the class
Freight class isn't negotiable the way a rate might be — it's a classification based on the physical properties of your freight.