LTL (less-than-truckload) shipping prices a small shipment partly by its freight class, and in the National Motor Freight Classification (NMFC) system, density is a large part of how that class is set. Many LTL billing disputes start with a wrong measurement, not a wrong rate. This guide explains what freight class is, shows the density calculation that NMFTA publishes, works through two examples, and lists what to check before a carrier re-weighs or re-measures a shipment. The classification works the same way whichever LTL carrier moves the freight: NMFTA says LTL rates are based on its freight classifications.
What Freight Class Is
The National Motor Freight Traffic Association (NMFTA) publishes the NMFC. It describes freight class as the "common language of shipping": each commodity gets a class from 50 to 500, based on four transportation characteristics:
| Characteristic | NMFTA's description |
|---|---|
| Density | How heavy the freight is relative to the space it takes up |
| Handling | How easy it is to move across a dock and into or out of a trailer |
| Stowability | How effectively it can be stowed in a trailer for transport |
| Liability | How likely the freight is to cause damage or be damaged |
NMFTA summarizes the effect this way: the denser and easier to move, the lower the class, and the lower the cost. A shipment's class is only part of the price, since carriers also apply their own rate tariffs, minimum charges and accessorial fees, which this article does not cover.
How Density Is Calculated
NMFTA's published FAQ on the classification changes gives the method. For a handling unit:
- Multiply the greatest straight-line length, width and height, in inches, including any projections, as the unit is tendered to the carrier.
- Divide that total by 1,728 cubic inches (one cubic foot) to get the cubic feet.
- Divide the weight of the handling unit as tendered by the cubic feet. The result is the density in pounds per cubic foot (pcf).
NMFTA's own example is boxes unitized on a lift-truck pallet measuring 48" × 40" × 45" and weighing 450 pounds. The steps are: 48 × 40 × 45 = 86,400 cubic inches; 86,400 ÷ 1,728 = 50 cubic feet; 450 ÷ 50 = 9.00 pcf.
You can run the same three steps for your own pallet with the LTL Density Calculator.
NMFTA's guidance on getting this right is practical: measure accurately, down to the inch, and always include pallets or packaging, and do not assume an irregular item behaves like a standard box. Its example of why it matters is that an item that ships at 15 pcf might fall into a lower class than the same item at 5 pcf.
A Second Worked Example (Hypothetical)
A pallet of packaged goods is stacked to 52" long, 44" wide and 60" high including the pallet, and weighs 600 pounds. The volume is 52 × 44 × 60 = 137,280 cubic inches. Dividing by 1,728 gives 79.44 cubic feet. The density is 600 ÷ 79.44 ≈ 7.55 pcf. If the shipper had measured only the cargo and left out a 6-inch pallet, the height would be 54". The volume would be 123,552 cubic inches, or 71.5 cubic feet. The density would then appear to be 600 ÷ 71.5 ≈ 8.39 pcf. The difference between 7.55 and 8.39 is the kind of understatement that can lead a carrier to reclassify the shipment after inspection. What each density means in class terms depends on the item's NMFC number and the current tables, not on this article.
Multiple Handling Units
NMFTA's FAQ cites NMFC Item 110, Section 8(d). Unless otherwise provided, where a shipment consists of multiple handling units, the density is calculated on each handling unit. The exception is where the shipping papers show only a total weight for all units tendered. In that case density may be calculated using the total weight and total cube. Listing the weight and dimensions of each pallet on the bill of lading gives the carrier what it needs and avoids a total-only calculation that may not match each unit. NMFTA noted that the mixed-commodity pallet rules were outside the scope of the 2025 changes it was describing.
What Changed in 2025
NMFTA reorganized parts of the NMFC in 2025 so that density plays a larger role for many commodities. Its FAQ describes the density scale being expanded from 11 to 13 subprovisions. As proposed there, sub 11 would apply to densities from 30 up to but not including 35 pcf at class 60. Sub 12 would apply from 35 up to but not including 50 pcf at class 55. Sub 13 would apply at 50 pcf or greater at class 50. That FAQ was written before the docket took effect and uses conditional wording, so treat those figures as the proposal described in it. NMFTA states that its ClassIT+ tool is the official source for item changes, density scales and rule updates. The current class for a specific item should be taken from there, not from a general article. Items with special handling, stowability or liability issues get classes based on those characteristics rather than on the density scale.
Checklist Before Tendering an LTL Shipment
- Find the correct NMFC item number for the commodity and confirm its current class and density rules in ClassIT+.
- Measure each handling unit at its greatest length, width and height, including pallet, packaging and any projections, as it will be tendered.
- Weigh each unit as tendered, and put weights and dimensions for every unit on the bill of lading.
- Calculate density with the three steps above and keep the working.
- Keep photos or a measurement record in case the carrier re-measures and issues a reclassification.
The class for a specific commodity depends on its NMFC item number and the current NMFTA tables, and carrier rates, discounts and accessorials come from each carrier's tariff or contract. For parcel dimensional weight, which is a different system, there is a calculator in our free tools; for loss or damage, see Freight Claims: Loss and Damage Deadlines and Carrier Duties.
Sources
Read from NMFTA's published pages on 11 October 2026 (the pages carry no publication date). The 2025 changes are described from an NMFTA FAQ written before they took effect, so check ClassIT+ for the current class and density breaks.
