For freight classified by density, the freight class starts with how much the shipment weighs compared with the space it takes up. The NMFC 13-tier density scale maps that density to a freight class when the applicable NMFC item uses density-based classification.
That scale is becoming relevant to more freight. NMFC Docket 2026-2 proposes applying the existing 13-tier structure to additional commodity provisions. So before looking at those proposed changes, it helps to understand how the scale works and how a shipment’s density is matched to a class.
What Is the NMFC 13-Tier Density Scale?
In NMFC, the 13-tier density scale is a classification structure that matches freight density, measured in pounds per cubic foot (pcf), with a freight class.
The scale has 13 density ranges. Each range corresponds to a freight class, starting with Class 400 for freight below 1 pcf and ending with Class 50 for freight at 50 pcf or greater. In general, lower-density freight falls into a higher class, while denser freight moves toward a lower class.
The 13-tier structure evolved from an earlier 11-tier density scale. Docket 2025-1 changed the last density range and added two more, bringing the total to 13.
To find where a shipment falls on this scale, you first need one number: its density.
How Do You Calculate Freight Density for the NMFC Scale?
Freight density tells you how much weight is packed into the space a shipment takes up. Start with the shipment’s length, width, and height. Those dimensions tell you how much space the freight occupies.
If the dimensions are in inches, multiply them together and divide by 1,728 to get cubic feet. Use the greatest length, width, and height of the shipment, including anything that sticks out.
Say a pallet measures 48 × 40 × 48 inches and weighs 500 pounds.
Multiplying the three dimensions gives 92,160 cubic inches. Divide that by 1,728, and the pallet takes up about 53.3 cubic feet.
Now divide the pallet’s 500-pound weight by its 53.3 cubic feet of space:
500 ÷ 53.3 = 9.4 pcf
So the pallet’s density is 9.4 pounds per cubic foot. With that number in hand, you’re ready to find where it falls on the 13-tier NMFC density scale.
| Sub-provision | Density in Pounds per Cubic Foot | Freight Class |
|---|---|---|
|
1 |
Less than 1 pcf |
400 |
|
2 |
1 but less than 2 pcf |
300 |
|
3 |
2 but less than 4 pcf |
250 |
|
4 |
4 but less than 6 pcf |
175 |
|
5 |
6 but less than 8 pcf |
125 |
|
6 |
8 but less than 10 pcf |
100 |
|
7 |
10 but less than 12 pcf |
92.5 |
|
8 |
12 but less than 15 pcf |
85 |
|
9 |
15 but less than 22.5 pcf |
70 |
|
10 |
22.5 but less than 30 pcf |
65 |
|
11 |
30 but less than 35 pcf |
60 |
|
12 |
35 but less than 50 pcf |
55 |
|
13 |
50 pcf or greater |
50 |
The pattern is easy to follow. Lower-density freight sits higher on the class scale, while denser freight moves toward the lower classes.
Take the 9.4 pcf from the example above. For the shipper, that means the freight falls between 8 and less than 10 pcf on the table, which points to Class 100.
Before using the table, check the NMFC item for the freight. Make sure that item uses the 13-tier density scale. Once it does, you can use the density number to find the class.
How Does NMFC Docket 2026-2 Expand the Use of the 13-Tier Density Scale?
The same 13-tier scale is now showing up in more proposals under NMFC Docket 2026-2. The docket does not change the 13 density ranges. Instead, it proposes using the existing scale for additional commodity groups.
Those proposals include glassware, building woodwork, ladders, fish, fencing, earthen conduits, farm equipment, shades or blinds, and vehicle parts. For these groups, the proposed class structure relies more directly on density where the standard 13-tier scale applies.
That does not mean every commodity will move to the 13-tier scale. Some freight still has other factors that affect how it is classified, which is why the NMFC item for the product still needs to be checked.
For now, these Docket 2026-2 changes remain proposals. The FCDC Disposition Bulletin on October 9, 2026, will show which proposals move forward.
When Does the Standard 13-Tier Density Scale Not Apply?
The 13-tier scale does not apply to every NMFC item. Some freight is classified using more than density because the way it is handled, stored in a trailer, packaged, or exposed to damage also affects its class.
That is why the NMFC item still needs to be checked first. Some items have specific rules tied to handling, stowability, liability, packaging, or the shipment’s greatest dimension. In those cases, density alone does not decide the class.
Docket 2026-2 shows this in the proposed changes to Item 640 for certain mixed handling units. If one of the articles has special handling, stowability, or liability conditions, a hazardous-material symbol, or a class based on packaging, dimensions, or another factor besides density, the proposal uses the highest class among those articles instead of classifying the handling unit only by density.
So, the 13-tier table is a useful reference, but only after the shipper confirms that the NMFC item actually uses it. That check is what keeps the density calculation tied to the right freight class.
How Does the 13-Tier Density Scale Help Shippers Classify Freight?
For shippers, the 13-tier scale gives a fixed reference for turning a density value into a freight class.
Once the correct NMFC item is confirmed, the shipper only needs to match the shipment’s density with the right range in the table. That makes the class easier to check before the freight moves.
It also shows why final shipment data matters. If the dimensions or weight change, the density may move into another range and the freight class may change with it.
Once the density is in hand, shippers have a direct way to check where the freight falls on the class table.