Freight Class Explained (How to Find Your NMFC Class)
US domestic LTL shipments are priced by freight class. Here is what class means, how density determines it, the full lookup table, and a worked example.
Freight class is the NMFC category that prices US LTL shipments, running from 50 (dense) to 500 (light and bulky). The main driver is density: divide total weight in pounds by total volume in cubic feet, then look the result up on the density scale. A pallet at 9.375 lb/ft³ falls into class 100.
What freight class is
In the United States, LTL (less-than-truckload) freight is priced using a standardized system called the NMFC (National Motor Freight Classification). Every shipment is assigned one of 18 classes from 50 to 500. A lower number means denser, easier-to-handle freight that costs less per pound; a higher number means light, bulky or fragile freight that costs more.
For the great majority of shipments, the class is driven by density — pounds per cubic foot — which is the part you can calculate yourself.
How to calculate it
Two steps get you to density, and density gets you to class:
cubic feet = L × W × H (in) ÷ 1,728
density (lb/ft³) = total weight (lb) ÷ cubic feet
The 1,728 converts cubic inches to cubic feet (12 × 12 × 12). Once you have density, read off the class from the table below — the class is the first bucket whose lower bound your density meets or exceeds.
Worked example
One pallet, 48 × 40 × 48 in, weighing 500 lb:
| Step | Calculation | Result |
|---|---|---|
| Cubic inches | 48 × 40 × 48 | 92,160 in³ |
| Cubic feet | 92,160 ÷ 1,728 | 53.33 ft³ |
| Density | 500 ÷ 53.33 | 9.375 lb/ft³ |
| Class | 9.375 is ≥ 9 | Class 100 |
So this pallet ships as class 100. If you compressed the same 500 lb into half the volume, density would double to ~18.75 lb/ft³ and the class would drop to 65 — cheaper to ship.
The density-to-class table
This is the standard 18-step NMFC density scale. Find the row your density meets or exceeds:
| Density (lb/ft³) | Class |
|---|---|
| 50 and over | 50 |
| 35 – 50 | 55 |
| 30 – 35 | 60 |
| 22.5 – 30 | 65 |
| 15 – 22.5 | 70 |
| 13.5 – 15 | 77.5 |
| 12 – 13.5 | 85 |
| 10.5 – 12 | 92.5 |
| 9 – 10.5 | 100 |
| 8 – 9 | 110 |
| 7 – 8 | 125 |
| 6 – 7 | 150 |
| 5 – 6 | 175 |
| 4 – 5 | 200 |
| 3 – 4 | 250 |
| 2 – 3 | 300 |
| 1 – 2 | 400 |
| Under 1 | 500 |
What density doesn't capture
Density gets you the right class for most freight, but the complete NMFC system weighs three more factors: stowability (odd shapes, hazmat), handling (fragile or hard-to-load goods), and liability (value and theft/damage risk). Some commodities carry a fixed class regardless of density, so confirm against the NMFC listing for your goods.
Density also drives air and ocean pricing in a different form — see volumetric weight vs actual weight for how the same idea applies as dimensional weight, and boxes per pallet for getting your shipment denser.
Frequently asked questions
What is freight class?
Freight class is the standardized category US LTL carriers use to price less-than-truckload shipments, defined by the NMFC system. There are 18 classes from 50 (dense, cheap to ship) to 500 (light and bulky, expensive). Density is the main driver.
How do I calculate freight class?
Work out density in pounds per cubic foot: total weight (lb) divided by total volume (ft³). Then look that density up on the NMFC density scale. For example, 9.375 lb/ft³ falls into class 100.
How do I find the cubic feet of my shipment?
Multiply length × width × height in inches, then divide by 1,728 (the number of cubic inches in a cubic foot). A 48 × 40 × 48 in pallet is 92,160 ÷ 1,728 = 53.33 ft³.
Is freight class only about density?
Density is the primary factor and the one you can calculate. The full NMFC system also considers stowability, ease of handling and liability (value and fragility), which can move some commodities to a fixed class regardless of density.
What is a lower freight class better?
Lower class numbers (like 50 or 60) mean denser freight, which is cheaper to ship per pound. Higher numbers (like 250 or 400) mean light, bulky or fragile freight that costs more. Maximizing density lowers your class and your cost.
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