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 NMFC restructure that took effect July 19, 2025 (Docket 2025-1), classification leans much more heavily on density — weight per cubic foot — for 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 — this is the full 18-class density scale our calculator uses:

Density (lb/ft³)	Class
50+	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

Example: a 48×40×48-inch pallet weighing 600 lb. Volume = (48×40×48) ÷ 1,728 = 53.33 ft³. Density = 600 ÷ 53.33 = 11.25 lb/ft³ → class 92.5 (the 10.5–12 band).

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.