How freight class is figured
LTL carriers price most freight by class, from class 50 for dense, sturdy freight to class 400 for light, bulky freight. For a growing share of commodities the class comes from density alone, the weight for the space a unit takes on the trailer:
- Measure each handling unit at its extreme points: length, width and height in inches, pallet and any overhang included. Round a fraction of an inch up, so the size you declare is never smaller than what the carrier measures.
- Find the cubic feet: length × width × height ÷ 1,728.
- Find the density: weight ÷ cubic feet, in pounds per cubic foot (lb/ft³).
- Look up the class on the density scale below.
Example: a 48 × 40 in pallet stacked to 48 in, 500 lb with the pallet. 48 × 40 × 48 = 92,160 in³, ÷ 1,728 = 53.3 ft³. 500 ÷ 53.3 = 9.38 lb/ft³, which falls between 8 and 10: class 100. Three more inches off the top (45 in) or 34 lb more freight would make it 10 lb/ft³ and class 92.5.
Freight class and the NMFC
Freight classes come from the National Motor Freight Classification (NMFC), published by the National Motor Freight Traffic Association (NMFTA). According to NMFTA, each commodity gets a class from 50 to 500 based on four characteristics:
- Density: how heavy the freight is for the space it takes.
- Handling: how easy it is to move across a dock and into or out of a trailer.
- Stowability: how well it can be stowed in a trailer.
- Liability: how likely it is to cause damage or be damaged.
The denser and easier to move, the lower the class and the cost. Each commodity has an NMFC item number (the “NMFC code”) that sets its class, either a fixed one or one from the density scale below. NMFTA’s ClassIT+ looks up item numbers; this calculator handles the density part.
The NMFC density scale
The scale since NMFC Docket 2025-1 took effect on July 19, 2025. Each step starts at the density shown and runs up to the next one.
| Density (lb/ft³) | Class |
|---|---|
| Less than 1 | 400 |
| 1 to less than 2 | 300 |
| 2 to less than 4 | 250 |
| 4 to less than 6 | 175 |
| 6 to less than 8 | 125 |
| 8 to less than 10 | 100 |
| 10 to less than 12 | 92.5 |
| 12 to less than 15 | 85 |
| 15 to less than 22.5 | 70 |
| 22.5 to less than 30 | 65 |
| 30 to less than 35 | 60 |
| 35 to less than 50 | 55 |
| 50 or more | 50 |
The full chart with the old scale side by side is on the freight class chart; what changed and when is in NMFC density changes.
Several pallets in one shipment
Each handling unit is classed on its own density, so a light pallet and a heavy one in the same shipment can travel at different classes. NMFTA’s Docket 2026-1 says it plainly: each individual handling unit is assigned a freight class based on its calculated density. Add a line for each kind of unit and set how many of each there are. The calculator also shows the average density of the whole shipment, total weight over total cubic feet, because some carriers’ tariffs figure density on the whole shipment: XPO’s divides the total weight of the shipment by its total cubic feet.
Before you book
- The density scale applies to commodities whose NMFC item says so. Some items keep a fixed class; check yours in the NMFC or with your carrier.
- Put the dimensions on the bill of lading. A carrier that measures more cube than you declared will reclass the shipment and add a charge.
- Very large, light shipments may be billed by the space they take instead. Pitt Ohio's tariff, for example, applies its cubic capacity rule at 750 ft³ or more with an average density under 6 lb/ft³, and its linear foot rule at 12 linear feet of trailer or more. The calculator flags the first.
- Tall freight: XPO's tariff figures the cube of any article 75 in or taller as if it were 96 in tall.
Questions
How do I calculate freight class?
Measure the handling unit (pallet, crate or piece) at its longest, widest and tallest points in inches, multiply them and divide by 1,728 to get cubic feet. Divide the weight by the cubic feet to get the density in pounds per cubic foot, then look the density up on the NMFC density scale. A 48 × 40 × 48 in pallet weighing 500 lb is 53.3 ft³ and 9.38 lb/ft³, which is class 100.
What changed in freight class in 2025?
NMFC Docket 2025-1 took effect on July 19, 2025. It moved thousands of commodities from fixed classes to the density scale, and the scale grew from 11 to 13 steps: freight of 35 to under 50 lb/ft³ is now class 55, and 50 lb/ft³ or more is class 50. Before, everything from 30 lb/ft³ up was class 60. See the NMFC changes.
Is a lower freight class cheaper?
Yes. Class 50 is the densest, easiest freight and the cheapest per pound; class 400 is the lightest for its size and the most expensive. The calculator shows how much weight, or how many inches less height, would move your unit to the next cheaper class.
Does the pallet count in the density?
Yes. Density is figured for each handling unit as you tender it, so the pallet is part of the height and of the weight. Carriers’ rules tariffs say the same: XPO’s counts the pallet, platform or skid as part of the shipping package. If you measured only the boxes, answer “No, add a 48 × 40 pallet” in the calculator.
Why did my carrier reclass my shipment?
Carriers measure and weigh freight at the dock. If the unit is bigger or lighter than the bill of lading says, the density drops and the class goes up, and the invoice is corrected with a fee on top: XPO’s tariff, for example, charges a $47.85 correction fee when an inspection raises the charges. Units close to a class break are the most at risk: the calculator warns when one inch more on each side would change the class.
What is an NMFC code?
An NMFC code, or NMFC item number, points to a commodity in the National Motor Freight Classification, the standard published by NMFTA. The item says which class the commodity ships at: a fixed class, or a class from its density. In NMFTA’s words, using the correct item number means fewer billing surprises.
How do I find my NMFC code?
NMFTA, which publishes the NMFC, offers ClassIT+ to search for the correct NMFC item number, calculate density and confirm the class; your carrier or broker can also tell you. Item descriptions are NMFTA’s copyright and are not reproduced on this site. For an item that classes by density, this calculator gives you the class.
Is this an NMFC calculator?
It calculates density and the class on the general NMFC density scale (13 steps, in force since July 19, 2025), the same scale NMFTA’s Docket 2026-1 lists. It does not look up NMFC item numbers.
Can I use density for every commodity?
No. Many NMFC items still have a fixed class, or a density scale with their own breaks, because of how they handle, stow or how liable they are to damage. The density scale here is the general one. Check the NMFC item for your commodity, or ask your carrier or broker, before you book.