How this calculator works
Less-than-truckload carriers group freight into classes numbered from 50 to 500. Low classes cover dense, easy freight and high classes cover light, bulky freight that fills a trailer before it reaches the weight limit. The National Motor Freight Classification uses density, stowability, handling and liability, and for ordinary goods density decides the class. Density is the shipment weight divided by its cubic volume. This page uses pounds per cubic foot, the unit in the class table, and also shows kilograms per cubic metre. Freight that is 9.8 pounds per cubic foot falls in class 100.
Formula
density (lb/ft³) = weight in pounds / volume in cubic feet. density (kg/m³) = weight in kilograms / volume in cubic metres. one lb/ft³ = 16.018463 kg/m³. freight class = the band the density falls in: under 1 is class 400, 1 to under 2 is 300, 2 to 4 is 250, 4 to 6 is 175, 6 to 8 is 125, 8 to 10 is 100, 10 to 12 is 92.5, 12 to 15 is 85, 15 to 22.5 is 70, 22.5 to 30 is 65, 30 to 35 is 60, 35 to 50 is 55, and 50 or more is 50.
Worked example
A pallet load of 120 by 100 by 120 centimetres weighs 227 kilograms. The volume is 1.2 x 1.0 x 1.2 = 1.44 cubic metres, so the density is 227 / 1.44 = 157.6 kilograms per cubic metre. Dividing by 16.0185 gives 9.84 pounds per cubic foot, which falls in the 8 to under 10 band, so the freight class is 100.
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Frequently asked questions
Is density the only thing that sets the class?
No. The classification also considers how easily the freight can be stowed, how hard it is to handle and how likely it is to be damaged or stolen. Dense but awkward items can be placed in a higher class than density alone suggests, and some commodities have their own item number. Use this page as a density estimate and confirm with the carrier.
Why does a higher class cost more?
A class 400 shipment of light, bulky goods occupies trailer space that could otherwise carry heavier freight. Rating by class spreads the cost of that space across the shipment. Dense freight reaches the trailer weight limit in a small volume, so it is cheaper per pound.
How should I measure the volume?
Measure the load as it will ship, including the pallet and any overhang, and round up to whole inches or centimetres. Carriers may reweigh and remeasure, and a small increase in height can lower the density enough to move a shipment to a higher class.
Does the class apply to full truckloads?
Not usually. Truckload shipments are priced by the mile and the load, not by class. Class matters for less-than-truckload freight, where the carrier consolidates several shipments in one trailer.