Freight Class Explained: How NMFC Classes Work
Freight class is a standardized number — from 50 to 500 — that the LTL industry uses to price your shipment. It comes from the National Motor Freight Classification (NMFC), maintained by the NMFTA. Lower classes are dense, sturdy, easy-to-handle freight that’s cheap to ship; higher classes are light, bulky, or fragile freight that costs more.
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.
What determines your class
Historically the NMFC weighed four factors: density, stowability, handling, and liability. Since the 2025 NMFC restructure, the system leans much more heavily on density — weight per cubic foot — for most general commodities. For the majority of freight, if you know your density, you can estimate your class.
The density formula
volume (cubic feet) = (length × width × height in inches) ÷ 1,728
density (lb/ft³) = weight (lb) ÷ volume (cubic feet)Then map density to class:
| Density (lb/ft³) | Class |
|---|---|
| 50+ | 50 |
| 30–35 | 60 |
| 22.5–30 | 65 |
| 15–22.5 | 70 |
| 12–13.5 | 85 |
| 9–10.5 | 100 |
| 6–7 | 150 |
| 4–5 | 200 |
| 2–3 | 300 |
| 1–2 | 400 |
| under 1 | 500 |
(That’s an abbreviated table — our calculator uses the full 18-class scale.)
Example: a 48×40×48-inch pallet weighing 600 lb. Volume = (48×40×48) ÷ 1,728 = 53.3 ft³. Density = 600 ÷ 53.3 = 11.3 lb/ft³ → roughly class 85.
Why getting it right matters
Carriers can and do re-weigh and re-measure your freight at the terminal. If your declared class is too low, you’ll get a reclassification plus a corrected (higher) invoice — and sometimes a fee. Declare too high and you quietly overpay on every shipment.
The honest truth: density-based estimates are accurate for most freight, but some commodities have fixed NMFC item numbers that override density. That gap is exactly why it pays to work with a broker who knows the classifications.
Calculate yours
Run the free freight class calculator → — enter dimensions and weight, get an estimated class in seconds. Then get competing quotes from brokers in your lane.
Freight class estimates are for informational purposes only and are not a guarantee of final classification or cost.