How LTL freight class is determined: density, the NMFC scale and a worked example
The short version
- Density = weight in pounds ÷ volume in cubic feet. Volume is length × width × height in inches, divided by 1,728.
- Measure the shipment as tendered: pallet included, at its tallest and widest points, including any overhang.
- The NMFC density scale has 13 bands. Density moves a shipment between classes in steps, so a small change near a band boundary can change the class.
- Not every commodity is classed by density. Some carry a fixed class, and others are classed on handling, stowability or liability. The NMFC item for your commodity says which applies.
- Carriers inspect and reweigh freight. A reclassification on inspection is billed, so the dimensions on the bill of lading need to be the real ones.
For many commodities, LTL freight class is set by density: the shipment's weight in pounds divided by its volume in cubic feet. The density is read against the National Motor Freight Classification scale, which since July 19, 2025 has run in 13 bands from class 50, for freight of 50 pounds per cubic foot or more, to class 400, for freight under one pound per cubic foot. A standard 48 by 40 inch pallet stacked 48 inches high and weighing 400 lb has a density of 7.5 and ships as class 125. Lower the same freight to 40 inches high and it becomes class 100.
Class matters because LTL tariffs are published by class, and higher classes generally carry higher rates per hundredweight, although the terms of your agreement can change the billed result. Getting class wrong in either direction is expensive: too high and you overpay on every shipment, too low and the carrier reclassifies the freight on inspection and bills the difference, often with a fee.
How to calculate density
- Measure length, width and height in inches at the extremes of the shipment, including the pallet and anything that overhangs it.
- Multiply them and divide by 1,728 to get cubic feet.
- Weigh the shipment as tendered, including the pallet and packaging.
- Divide the weight by the cubic feet. The result is pounds per cubic foot.
- Find the band the density falls in on the scale below.
The NMFC density scale
| Density, lb per cubic foot | Class |
|---|---|
| Less than 1 | 400 |
| 1 but less than 2 | 300 |
| 2 but less than 4 | 250 |
| 4 but less than 6 | 175 |
| 6 but less than 8 | 125 |
| 8 but less than 10 | 100 |
| 10 but less than 12 | 92.5 |
| 12 but less than 15 | 85 |
| 15 but less than 22.5 | 70 |
| 22.5 but less than 30 | 65 |
| 30 but less than 35 | 60 |
| 35 but less than 50 | 55 |
| 50 or greater | 50 |
A worked example: one pallet, three ways
A standard 48 by 40 inch pallet of goods weighing 400 lb including the pallet.
| Shipment | Cubic feet | Density | Class |
|---|---|---|---|
| 48 × 40 × 48 in, 400 lb | 53.33 | 7.50 | 125 |
| 48 × 40 × 40 in, 400 lb | 44.44 | 9.00 | 100 |
| 48 × 40 × 48 in, 600 lb | 53.33 | 11.25 | 92.5 |
The first row is the starting point: 92,160 cubic inches is 53.33 cubic feet, and 400 lb over 53.33 is 7.5 pounds per cubic foot, in the 6 to 8 band, so class 125. Restack the same freight to 40 inches and the density rises to 9.0, class 100, one band cheaper with nothing about the goods changed. Load 600 lb into the original footprint and the density is 11.25, class 92.5. Open this example in the freight class calculator and change the height or the weight.
The practical point is that height is often the cheapest variable to change. A pallet built tall to save floor space in a warehouse can cost a class or more on every shipment, and the difference between class 125 and class 100 is a material share of the line haul.
Where shippers lose money on class
Reclassification. Carriers measure freight with dimensioners at their terminals. When the measured density puts the freight in a higher class than the bill of lading, the carrier rebills at the higher class, often with an inspection fee. Dimensions entered from a product spec rather than measured on the finished pallet are the usual cause.
Classing too high. The opposite error is quieter. A shipper who set a class years ago, before the density rules changed or before the packaging did, can be paying a higher class than the freight now measures. Nothing on an invoice flags it.
Class in the agreement. Many LTL agreements set a freight-all-kinds rule that rates mixed freight at a single class, or a floor or ceiling on the class billed. Those terms can override density, and whether they still fit your freight is a negotiation question.
What the calculator does not account for
The calculator applies the published density scale. It does not identify your NMFC item number or confirm that your commodity is classed by density: the full classification is licensed by the NMFTA, and the calculator does not reproduce that database. Confirm that your NMFC item uses this scale before treating the calculated class as final. It does not apply freight-all-kinds or other class terms in your agreement, and it does not price the shipment: LTL rates depend on the carrier's tariff, your discount and the lane. Use it to check that the class on your bill of lading matches what the freight measures.
Our LTL freight audit reviews reweighs, reclassifications and billed class against your shipment records, and our LTL contract negotiation work covers freight-all-kinds terms and class floors.
Frequently asked questions
How do I find my freight class?
If your commodity is classed by density, measure the shipment as tendered, calculate cubic feet by multiplying the dimensions in inches and dividing by 1,728, divide the weight by the cubic feet, and read the density against the NMFC scale. If your commodity has a fixed class or is classed on other characteristics, the NMFC item for it gives the class, through the NMFTA's ClassIT+ service.
What changed in the NMFC on July 19, 2025?
The changes moved many commodity listings to density-based classification and expanded the standard density scale to 13 bands from the earlier 11. Shippers whose freight was classed under the old rules may find the class has changed.
Does the pallet count in freight class density?
Yes. Density is calculated on the shipment as tendered, so the pallet's weight is included in the weight and its footprint and height are included in the dimensions.
What is a freight reclassification charge?
It is the difference billed when a carrier inspects a shipment and finds its class higher than the bill of lading states, usually because the measured density is lower. Many carriers add an inspection fee. Measuring the finished pallet, not the product specification, prevents most of them.
Is freight class the same as NMFC code?
No. The NMFC item number identifies the commodity; the freight class is the rating that item carries. For density-based items, the class depends on the measured density, so the same item can ship at different classes.
Sources
- National Motor Freight Traffic Association, National Motor Freight Classification, density-based subprovisions effective July 19, 2025, for the 13-band density scale, and ClassIT+ for item lookups. Our coverage of the change was published the day it took effect.
- The example pallet is illustrative and matches the default in the freight class calculator.