A mixed shipment may contain different articles that do not share the same freight class. Under proposed Item 640 in NMFC Docket 2026-2, more attention shifts to how those articles are grouped into individual handling units and the weight and dimensions recorded for each one.
Those measurements are used to work out handling unit density, which then becomes relevant to freight class for certain mixed shipments. To see how the proposal works, the first step is understanding what counts as a handling unit and what its density actually represents.
What is handling unit density?
A handling unit is freight that moves as one piece. It might be a pallet, skid, crate, or another load that has been grouped together for shipping.
Handling unit density is simply the weight of that unit compared with the space it takes up. NMFC expresses that number in pounds per cubic foot, or pcf.
Take a 500 lb pallet that occupies 50 cubic feet. Its density is 10 pcf. Keep the weight at 500 lb but make the pallet taller or larger, and the density goes down. Fit the same weight into less space, and the density goes up.
To work out that space, NMFC uses the greatest length, width, and height of the handling unit, including any projections or overhangs. Those outside measurements give the total cube used for the density calculation.
How is handling unit density calculated under the current NMFC rule?
Under current NMFC Item 110, when a shipment has multiple handling units, density is generally calculated separately for each handling unit.
So if a shipment has three pallets, each pallet is normally looked at on its own. Its weight and the space it takes up are used to find its density.
There is one exception. If the shipping papers list only the total weight for all handling units, density may be worked out using the total shipment weight and the total cube.
For one handling unit, the first step is to find how much space it takes up:
Length × Width × Height ÷ 1,728 = Cubic feet
Then divide the weight by that cubic space:
Handling unit weight ÷ Cubic feet = Density in pcf
What does a handling unit density calculation look like?
Take a pallet that measures 48 × 40 × 48 inches and weighs 500 lb.
First, find the cube:
(48 × 40 × 48) ÷ 1,728 = 53.3 ft³
Now use that cube with the pallet weight:
500 ÷ 53.3 = 9.4 lb/ft³
So this pallet has a handling unit density of 9.4 pcf.
The way density is worked out is not what Docket 2026-2 is proposing to change. The bigger change is what happens with that density when freight class is assigned to certain mixed shipments.
What does NMFC Docket 2026-2 propose for handling unit density?
That is where proposed Item 640 comes in. For a shipment containing articles subject to two or more freight classes, the proposal puts more focus on the density of each handling unit when the freight is classified.
Under proposed Sec. 2, each article must be listed separately on the original bill of lading. Except for the situations covered under Sec. 3, each handling unit is then classified using the NMFC 13-subprovision density scale.
If the original bill of lading includes the weight and dimensions of each handling unit, those numbers are used to calculate its density, subject to carrier verification.
If that information is not available, the proposal gives the carrier two ways to work out density:
- Use the total shipment weight and the overall shipment cube
- Use the weight and dimensions of the individual packages or handling units
These changes are still part of NMFC Docket 2026-2 and remain proposals. Until the final disposition is published, shippers should not treat them as the current NMFC rule.
How does handling unit density affect freight class?
Once the handling unit density is known, that number is matched to a range on the NMFC 13-subprovision density scale. Where proposed Item 640 applies, that range points to the freight class for the handling unit.
Lower-density freight generally has a higher class number. For example, a density from 8 to less than 10 pcf is Class 100. A density from 6 to less than 8 pcf is Class 125. Across the full scale, the classes run from Class 400 for freight below 1 pcf to Class 50 for freight at 50 pcf or more.
This is where the size of the handling unit starts to make a difference. If the weight stays the same but the pallet takes up more space, its density drops. Once that density moves into another range, the freight class changes with it.
How does a change in handling unit density change freight class?
Take two pallets that both weigh 500 lb. The only difference is the height.
| Measurement | Handling Unit A | Handling Unit B |
|---|---|---|
|
Length |
48 in |
48 in |
|
Width |
40 in |
40 in |
|
Height |
48 in |
60 in |
|
Weight |
500 lb |
500 lb |
|
Cube |
53.3 ft³ |
66.7 ft³ |
|
Density |
9.4 pcf |
7.5 pcf |
|
Freight class |
Class 100 |
Class 125 |
Handling Unit A measures 48 inches high and has a density of 9.4 pcf. That puts it in the 8 to less than 10 pcf range, or Class 100.
Handling Unit B weighs the same 500 lb, but its height increases to 60 inches. That extra space lowers the density to 7.5 pcf, which moves it into the 6 to less than 8 pcf range, or Class 125.
The weight never changed. The dimensions did.
That is why the final size of the handling unit becomes so important when density is used for classification. A difference in length, width, or height changes the cube. That changes the density, and the new density places the handling unit in a different freight class.
When does handling unit density not determine the proposed class?
Density is not the deciding factor for every handling unit under proposed Item 640.
Proposed Sec. 3 covers situations where an article is classified based on factors such as handling, stowability, liability, packaging, greatest dimension, or another factor besides density. When one of those conditions applies, the handling unit takes the class of the highest-classed article instead of receiving a class from its density alone.
So, the 13-subprovision density scale applies only when the handling unit meets the conditions for density-based classification under the proposal.
How does pallet dimensioning support handling unit density calculations?
If handling unit density depends on cubic space and weight, the dimensions used in that calculation need to reflect the final pallet as it ships.
vMeasure Pallet Ultima captures the pallet’s length, width, and height in under 2 seconds. When connected to a compatible, validated scale, the weight is added to the same measurement record. The record also includes the pallet image, shipment or barcode ID, and timestamp.
That gives the shipper the dimensional data first, along with the weight needed for the density calculation. Through configured integrations, the measurement record then moves into WMS, TMS, or other shipping systems through vMeasure Forge using REST APIs or webhooks.