How do I calculate freight class?

For an item the NMFC classes by density, measure length, width and height in inches including any overhang, multiply, divide by 1,728 for cubic feet, and divide the weight by that to get pounds per cubic foot — then read the class off the density scale. Many items have a fixed class instead, so look the item up in the NMFC first.

Does freight class apply outside the US?

The NMFC is a US standard used by US less-than-truckload carriers. Other markets usually price part loads on weight and the space the freight takes rather than on an NMFC class.

Term

Freight class

Freight class is a number from 50 to 500 that US less-than-truckload carriers use to price a shipment, set by the National Motor Freight Classification. It reflects four things — density, ease of handling, how well the freight stows in a trailer, and its liability to damage. Dense, sturdy freight gets a low class and a lower rate.

Also called NMFC freight class, LTL freight class, freight classificationApplies in USUpdated 12 October 2026

How a class is set

The National Motor Freight Traffic Association (NMFTA) gives every commodity in the NMFC a class from 50 to 500, judged on four characteristics:

Density — how heavy the freight is for the space it takes up.
Handling — how easily it moves across a dock and into or out of a trailer.
Stowability — how well it can be stowed in a trailer alongside other freight.
Liability — how likely it is to be damaged, or to damage other freight.

In NMFTA's words, the denser and easier to move, the lower the class — and the lower the cost. Bulky, fragile or hazardous items sit higher.

The 18 classes

Carriers publish one rate table per class: 50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400 and 500. FedEx Freight's 2026 zone-based rates, for example, carry a table for each.

Worked example: density sets the class

A pallet measures 48 × 40 × 45 in (122 × 102 × 114 cm) and weighs 450 lb (204 kg). For an item classed by density, the NMFC measures the full size and divides by 1,728 to get cubic feet:

Density = 450 lb ÷ (48 × 40 × 45 ÷ 1,728) = 450 ÷ 50 ft³ = 9 lb/ft³ (about 144 kg/m³)

On the NMFC's 13-step density scale, 8 to under 10 lb/ft³ is class 100. The same pallet at 350 lb is 7 lb/ft³ — class 125.

Suppose a carrier's rate on the lane is USD 48.20 per 100 lb at class 100 and USD 58.10 at class 125. The 450 lb pallet costs 4.5 × 48.20 = USD 216.90; the 350 lb pallet costs 3.5 × 58.10 = USD 203.35. A hundred pounds less freight saves only USD 13.55, because the lighter pallet still takes the same space.

The mistake people make

Leaving the class off the bill of lading or guessing it. Old Dominion's accessorial guide says a missing class or description defaults to class 100, and carriers reweigh and reinspect freight that looks wrong: FedEx Freight's rules add a USD 40 validation fee when a reweigh comes in 50 lb or more above the bill. NMFTA warned that its 2025 changes could bring misclassification and costly chargebacks for shippers who were not ready.

FAQ

Freight class: common questions

How many freight classes are there?: Eighteen, from class 50 to class 500: 50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400 and 500. Carriers publish a rate table for each.
How do I calculate freight class?: For an item the NMFC classes by density, measure length, width and height in inches including any overhang, multiply, divide by 1,728 for cubic feet, and divide the weight by that to get pounds per cubic foot — then read the class off the density scale. Many items have a fixed class instead, so look the item up in the NMFC first.
Does freight class apply outside the US?: The NMFC is a US standard used by US less-than-truckload carriers. Other markets usually price part loads on weight and the space the freight takes rather than on an NMFC class.

Sources

On Traqo: Freight Class Calculator turns size and weight into density and an estimated class.