The 13-step NMFC density scale, with worked examples
On July 19, 2025, the National Motor Freight Classification moved most commodities onto a single density scale with 13 steps. If your product has no special handling, stowability or liability concerns, its class is now decided by one number: pounds per cubic foot.
The table
| Sub | Density, lb per cu ft | Class |
|---|---|---|
| 1 | Less than 1 | 400 |
| 2 | 1 but less than 2 | 300 |
| 3 | 2 but less than 4 | 250 |
| 4 | 4 but less than 6 | 175 |
| 5 | 6 but less than 8 | 125 |
| 6 | 8 but less than 10 | 100 |
| 7 | 10 but less than 12 | 92.5 |
| 8 | 12 but less than 15 | 85 |
| 9 | 15 but less than 22.5 | 70 |
| 10 | 22.5 but less than 30 | 65 |
| 11 | 30 but less than 35 | 60 |
| 12 | 35 but less than 50 | 55 |
| 13 | 50 or greater | 50 |
Lower bounds are included and upper bounds are not. Exactly 15.0 lb per cu ft is class 70. A reading of 14.99 is class 85.
How to calculate density
- Measure each handling unit at its longest, widest and tallest points, in inches. Include the pallet, any overhang, and anything sticking out. A carrier's dimensioner measures the extreme points, so you should too.
- Multiply length by width by height, then divide by 1,728 to get cubic feet.
- Add up the cubic feet for all units, and add up the weight for all units, pallets and packaging included.
- Divide total weight by total cubic feet.
Worked example
Two pallets, each 48 x 40 x 50 inches and 720 lb.
- Cube per pallet: 48 x 40 x 50 = 96,000 cubic inches, or 55.56 cu ft
- Total: 111.1 cu ft and 1,440 lb
- Density: 1,440 / 111.1 = 12.96 lb per cu ft, which is class 85
Now suppose the carrier's dimensioner reads 54 inches high instead of 50, because a carton on top shifted. Cube becomes 120 cu ft, density drops to 12.0, and the shipment is still class 85, barely. At 55 inches it is 11.78 and class 92.5.
The point: five inches of height was the whole difference between two classes. Know how far you are from the next line down. If it is less than an inch or two, expect corrections on that lane and keep photos.
What the scale does not cover
- Commodities with their own rules. Items that are fragile, hazardous, hard to stow or high in value can carry a fixed class or extra conditions. Look up the NMFC item for your product before assuming density alone applies.
- FAK pricing. If your agreement rates a range of classes as one class, the agreement governs for the classes it names. A reclass can still push you outside the FAK range, which is when it costs you.
- Cubic capacity and linear foot rules. Large, light shipments can trigger a separate carrier rule that rerates the whole shipment. That is a tariff rule, not classification, and it is disputed differently.
How to use this in a dispute
When a corrected invoice arrives, do the arithmetic twice: once with your numbers and once with the carrier's. Three outcomes are possible.
- Both give the billed class. The correction is right. Fix your BOL.
- Your numbers give a lower class and theirs give the billed class. The dispute is about whose measurement is right, and evidence decides it.
- Neither gives the billed class. The carrier made an arithmetic or data-entry error. These are the easiest disputes to win.
The invoice checker does both calculations and tells you which case you are in.
Got a corrected invoice in hand?
Run it through the checker in about a minute, or send us the batch and we will tell you which ones are worth disputing. The audit is free.