How is freight class determined?
Freight class tells a less-than-truckload (LTL) carrier how easy or hard a shipment is to move. Classes come from the National Motor Freight Classification (NMFC), published by the National Motor Freight Traffic Association (NMFTA), and there are 18 of them, from class 50 to class 500. The lower the number, the easier the freight is to handle and the lower the rate tends to be. Four characteristics set the class: density, handling, stowability and liability.
Density is the one you can measure yourself. It's the weight of a handling unit (each pallet, crate or loose piece) divided by the space it takes up, in pounds per cubic foot. Light, bulky freight fills trailer space without adding much weight, so low density points to a higher class number and a higher rate. Dense freight works the other way. In LTL, higher density generally means a lower shipping cost, though not in every case.
On July 19, 2025, NMFC Docket 2025-1 moved the commodities it covers from commodity-based to density-based classes. The standard density scale (the NMFC table that maps lb/ft³ to a class) grew from 11 subs to 13, with the top three now covering classes 60, 55 and 50. That scale runs from class 50 to class 400, so it doesn't use every class in the system.
The scale is the standard for commodities with no special handling, stowability or liability issues. Items that do have those issues keep their own item-specific class, so you still need to check the NMFC item number (the entry that identifies your commodity and its class) for what you ship. The NMFC itself is a voluntary standard, and a carrier's own published tariff can take precedence. This calculator gives you the density-based estimate; your carrier's classification is the one that counts.
How to calculate density and freight class
Density for freight class is weight in pounds divided by volume in cubic feet. Measure each handling unit at its outside dimensions, as you'll hand it to the carrier: pallet, packaging and any overhang included. Use the longest point on each side, not the carton size. Weigh it the same way. The number that counts is the gross weight, meaning goods, packaging and pallet together. Since you measure in inches and a cubic foot is 1,728 cubic inches, the volume step always ends with ÷ 1,728.
- Measure the longest length, width and height of each handling unit in inches, including the pallet and any overhang.
- Multiply L × W × H, divide by 1,728 to get cubic feet, and multiply by the number of identical units.
- Weigh each unit as tendered, pallet and packaging included, to get the gross weight in pounds.
- Divide total pounds by total cubic feet. That's your density in lb/ft³.
- Find the band your density falls in on the density scale below, then check the NMFC item number. Some commodities have a fixed class that overrides density.
Example: one 48 × 40 in pallet
One standard 48 × 40 in pallet, loaded to 48 in high. Measured at the outside, pallet and packaging included, it's 48 × 40 × 48 in and weighs 900 lb gross. In metric, that's 121.92 × 101.6 × 121.92 cm and 408.2 kg.
| Dimensions (L × W × H) | 48 × 40 × 48 in |
| Volume in cubic inches | 92,160 in³ |
| Volume (÷ 1,728) | 53.33 ft³ |
| Gross weight | 900 lb |
| Density (900 ÷ 53.33) | 16.88 lb/ft³ |
| Density band | 15–22.5 lb/ft³ |
| Estimated class | Class 70 |
| Metric equivalent | 1.510 m³, 270.3 kg/m³ |
At 16.88 lb/ft³ (the calculator rounds it to 16.9), the pallet falls in the 15–22.5 band, which is class 70. Before you put that on the bill of lading, check the NMFC item number in case the commodity has its own class.
Density bands and freight classes
The 13-sub standard density scale in effect since Docket 2025-1. Each band includes its lower number and stops just below the upper one, so exactly 15 lb/ft³ is class 70. Commodities with an item-specific class don't follow this table.
| Density (lb/ft³) | Class |
|---|---|
| Under 1 | 400 |
| 1–2 | 300 |
| 2–4 | 250 |
| 4–6 | 175 |
| 6–8 | 125 |
| 8–10 | 100 |
| 10–12 | 92.5 |
| 12–15 | 85 |
| 15–22.5 | 70 |
| 22.5–30 | 65 |
| 30–35 | 60 |
| 35–50 | 55 |
| 50 or more | 50 |
Common mistakes
- Measuring the product instead of the handling unit. If you leave out the pallet, packaging or overhang, the volume comes out too small, density too high and the class too low. Carriers can re-measure and reclass the shipment.
- Leaving the pallet or packaging out of the weight. A 48 × 40 × 48 in pallet at 820 lb gross is 15.375 lb/ft³, class 70. Take off the pallet's roughly 37 lb and you get 783 lb, 14.68 lb/ft³ and class 85.
- Rounding dimensions down. A 48 × 40 in pallet at 440 lb that's really 50 in high is 55.56 ft³ and 7.92 lb/ft³, class 125. Write it down as 48 in and you get 53.33 ft³, 8.25 lb/ft³ and class 100, which understates the class and invites a reclass.
- Assuming every commodity is classed by density. Items with special handling, stowability or liability issues keep a fixed class, so check the NMFC item number.
- Mixing up per-unit and combined density. The NMFC rule is density per handling unit; total weight over total volume applies only when the shipping papers show just the total weight. This calculator uses the combined figure, so run very different pallets separately.
What is freight class?
Freight class is the NMFC rating that tells an LTL carrier how easy or hard a shipment is to move. The NMFC has 18 classes, from 50 to 500, set by four characteristics: density, handling, stowability and liability. The standard density scale used since Docket 2025-1 covers classes 50 to 400. Low-density freight lands in a higher class, which usually means a higher rate; dense freight lands in a lower class.
How do I calculate my NMFC freight class?
Measure the longest length, width and height of each handling unit in inches, including the pallet, packaging and any overhang, as it will be tendered. Multiply them and divide by 1,728 to get cubic feet. Divide the gross weight in pounds by the cubic feet to get density in lb/ft³, then find that density on the NMFC density scale. For example, a 48 × 40 × 48 in pallet at 900 lb is 53.33 ft³ and 16.88 lb/ft³, which falls in the 15–22.5 band: class 70.
Why does lower density mean a higher freight class?
A light, bulky shipment takes up a lot of trailer space for the weight it carries, and in LTL lower density generally means a higher shipping cost. Density is one of the four NMFC classification factors, alongside handling, stowability and liability. On the density scale, less than 1 lb/ft³ is class 400, while 50 lb/ft³ or more is class 50.
What happens if my freight class is wrong?
Carrier tariffs such as ODFL's let the carrier reweigh, inspect and check the density of a shipment when it thinks the bill of lading is incomplete or inaccurate. Estes, for example, can weigh freight without notice on NTEP-certified scales. A wrong class can lead to a reclass and a fee, and the amount depends on the carrier. ODFL charges $25 per shipment when an inspection leads to reclassification, and re-rates the freight charges, fuel surcharge and accessorial charges. Saia charges $44 per shipment when an inspection or reweigh changes the line haul (the main terminal-to-terminal move) charge. Estes charges $20 for an inspection and $20 for weighing.
Is every commodity classed by density?
No. The density scale is the standard for commodities with no special handling, stowability or liability issues, and Docket 2025-1 moved the items it covers to density-based classes on July 19, 2025. Commodities with those issues keep their own item-specific class, whatever their density. Check the NMFC item number for your goods, and remember that a carrier's own tariff can take precedence over the NMFC.
Why divide by 1,728?
One cubic foot is 12 × 12 × 12 inches, which is 1,728 cubic inches. Freight is measured in inches, so dividing length × width × height in inches by 1,728 converts the volume to cubic feet. Density for freight class is always weight in pounds per cubic foot.
Do I calculate density per pallet or for the whole shipment?
Under NMFC Item 110, Sec. 8(d), density is determined for each handling unit. The exception is when the shipping papers show only the total weight: then density is total weight divided by total volume. This calculator uses that combined method. It adds up the weight and volume of every row and returns a single density and class, not a class per pallet. If your pallets are very different, run each one on its own.
What's the difference between freight class and an NMFC item number?
The NMFC item number identifies the commodity in the classification, and the freight class is the rating that item carries. For many items the class depends on density; for items with special handling, stowability or liability issues, the item number carries a fixed class. You can look up item numbers and classes in NMFTA's ClassIT+, and both belong on the bill of lading.
What changed in freight class in 2025?
NMFC Docket 2025-1 took effect on July 19, 2025. It moved the commodities it covers from commodity-based to density-based classes and expanded the standard density scale from 11 subs to 13. The top three subs now cover classes 60 (30 to under 35 lb/ft³), 55 (35 to under 50 lb/ft³) and 50 (50 lb/ft³ or more).
Can I enter dimensions in centimeters and kilograms?
Yes. Switch the calculator to metric and enter centimeters and kilograms. It converts them to inches and pounds, so the results always show in lb/ft³, lb and ft³, the units the NMFC density scale uses.
Sources
- NMFTA — Major NMFC changes taking effect in 2025 (density-based classification)
- NMFTA — National Motor Freight Classification (NMFC) overview
All calculations run in your browser. Figures are based on published standards, carrier-published values and nominal dimensions, so check them against your carrier's own numbers before you book.
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