Why density drives your LTL freight class
Freight density is weight divided by volume, stated in pounds per cubic foot (lb/ft³, sometimes written pcf). For less-than-truckload (LTL) freight, the volume comes from the handling unit as you tender it (each pallet, crate or loose piece), measured at its greatest straight-line length, width and height in inches with every projection included. Cubic inches ÷ 1,728 gives cubic feet. The weight is the gross weight of that same unit: product, packaging and pallet.
The National Motor Freight Classification (NMFC) has 18 classes, from 50 to 500, set by four factors: density, handling, stowability and liability. Lower classes are easier to move and generally cost less. When Docket 2025-1 took effect on July 19, 2025, the items it covered switched from commodity-based to density-based classes, and the old 11-sub density scale gave way to a 13-sub scale that adds classes 55 and 50. Density is now the primary factor, but not the only one. Articles with handling, stowability or liability issues keep their own classes, so you still need the right NMFC item number. The NMFC is also a voluntary standard, and a carrier's own published tariff can take precedence over it.
In LTL, density usually decides the class, and higher density generally means a lower cost per pound. Carriers do check. Under its tariff, Old Dominion Freight Line (ODFL) can reweigh, inspect and confirm density when bill of lading details look incomplete or inaccurate, using portable electronic scales accurate to within 1%. Estes can weigh any shipment, with or without notice, on NTEP-certified legal-for-trade scales. If an ODFL inspection ends in a reclass, the shipment is re-rated, including fuel surcharge and accessorial charges, plus a $25 fee. Fees vary by carrier, so check your carrier's tariff.
How to calculate freight density
The method follows the NMFC rule: measure the handling unit the way you hand it to the carrier, not the product inside. Take the greatest straight-line length, width and height, not the circumference, and include the pallet, stretch wrap, overhang and anything else that sticks out. The divisor is 1,728 because a cubic foot holds 12 × 12 × 12 cubic inches. Weigh the complete unit as well.
Carriers compare what they measure with the bill of lading and shipping documents. The usual reasons for a higher invoice are the wrong class, an inaccurate weight estimate, and packaging left out of the dimensions.
- Measure length, width and height in inches at the widest and tallest points of each handling unit, with the pallet and any overhang included.
- Multiply length × width × height to get cubic inches.
- Divide cubic inches by 1,728 to get cubic feet. For identical units, multiply by the number of units.
- Add up the gross weight in pounds, pallet and packaging included.
- Divide the weight by the cubic feet to get density in lb/ft³.
- Look up the density on the 13-sub scale below. With mixed pallets, repeat these steps for each handling unit.
Example: one standard 48 × 40 in pallet
Take one 48 × 40 in pallet loaded to 48 in tall, pallet included, with a gross weight of 500 lb. These are the calculator's default inputs, so you can check the numbers above.
| Dimensions | 48 × 40 × 48 in |
| Volume | 92,160 in³ |
| ÷ 1,728 | 53.33 ft³ |
| Gross weight | 500 lb |
| Density | 9.4 lb/ft³ |
| Metric density | 150 kg/m³ |
| Freight class | 100 |
At 9.4 lb/ft³ the pallet sits in the 8 to under 10 lb/ft³ band, which is class 100. Put a lower class on the bill of lading and the carrier can reclass it, re-rate the freight and add an inspection fee.
Density to freight class: the 13-sub NMFC scale
Standard scale since Docket 2025-1; each band includes its lower bound, not its upper. Items with handling, stowability or liability issues keep their own class, and carrier tariffs can differ.
| Density (lb/ft³) | Class | Min. weight, 48 × 40 × 48 in |
|---|---|---|
| Under 1 | 400 | Under 53.3 lb |
| 1–2 | 300 | 53.3 lb |
| 2–4 | 250 | 106.7 lb |
| 4–6 | 175 | 213.3 lb |
| 6–8 | 125 | 320 lb |
| 8–10 | 100 | 426.7 lb |
| 10–12 | 92.5 | 533.3 lb |
| 12–15 | 85 | 640 lb |
| 15–22.5 | 70 | 800 lb |
| 22.5–30 | 65 | 1,200 lb |
| 30–35 | 60 | 1,600 lb |
| 35–50 | 55 | 1,866.7 lb |
| 50 and over | 50 | 2,666.7 lb |
Common mistakes
- Measuring the product instead of the unit. Leaving out the pallet, wrap or overhang shrinks the volume. Drop a 5.7 in pallet deck from the example and the density reads 10.64 lb/ft³, class 92.5 instead of 100, which is exactly what a reclass corrects.
- Measuring at the low or narrow side. The rule uses the greatest straight-line dimensions, so a bulging top layer or a carton sticking out sets the height or width.
- Dividing by 1,000 instead of 1,728. The volume comes out 1.728 times too large and the density about 42% too low: the example pallet drops from 9.4 to 5.4 lb/ft³, class 175 instead of 100. Skip the division altogether and the figure is off by three orders of magnitude.
- Rating mixed pallets as one. Each handling unit is classed on its own density unless the shipping papers show only a total weight. A 500 lb and a 150 lb pallet that are class 100 and class 175 separately come out at class 125 combined.
- Relying on an old item number. Items covered by Docket 2025-1 moved to density-based classes on July 19, 2025, so a class copied from an older bill of lading may no longer be right.
- Forgetting non-stackable freight. If nothing can go on top, ODFL and Saia may rate the unit at a height of at least 96 in, which lowers its density and can raise the class.
How do I calculate freight density?
Measure the length, width and height of the handling unit in inches at its greatest points, pallet and overhang included. Multiply them, divide by 1,728 to get cubic feet, then divide the gross weight in pounds by that figure. A 48 × 40 × 48 in pallet at 500 lb works out to 53.33 cubic feet and 9.4 lb/ft³, which is class 100.
Do I include the pallet when calculating freight density?
Yes. Density uses the weight of the handling unit as tendered, which is the gross weight of the product, packaging and pallet together. The dimensions include the pallet height, any overhang and every projection. If cartons are banded, strapped, wrapped or master-packed into one unit, you measure and weigh the finished unit, not the individual boxes.
Why does density determine freight class?
Since Docket 2025-1 took effect on July 19, 2025, the items it covered are classed by density instead of by commodity, and density is now the primary factor in the NMFC. It is not the only factor: freight with handling, stowability or liability issues keeps its own class, so check the NMFC item number. In LTL, higher density generally means a lower class and a lower cost per pound.
How do carriers check density, and what does a reclass cost?
Carriers compare their own measurements and scale weights with the bill of lading, and a mismatch can raise the invoice. ODFL's tariff lets it reweigh, inspect and confirm density, and charges $25 per shipment when an inspection leads to a reclass, on top of re-rating the freight. Estes charges $20 for an inspection and $20 for weighing. Amounts differ by carrier, so check the tariff of the carrier you use.
How can I lower my freight class by improving density?
Cut empty space: use cartons that fit the product, a pallet sized to the load, and avoid overhang, then run the numbers again. More weight in the same cubic feet raises density and can drop the class. Confirm the NMFC item number first, since articles with handling, stowability or liability issues are not classed on density alone. Watch non-stackable freight too, because a carrier may rate it at a height of at least 96 in.
Should I calculate density for each pallet or for the whole shipment?
The NMFC rule is to calculate each handling unit on its own. Combining total weight and total volume is allowed only when the shipping papers show just a total weight. A 500 lb pallet at 48 × 40 × 48 in (class 100) and a 150 lb pallet at 48 × 40 × 30 in (class 175) come out at 7.5 lb/ft³ and class 125 when combined. This calculator combines all rows, so enter one row at a time to see each unit's density.
Does a non-stackable pallet change its density?
It can. If nothing can be loaded on top because of the product, the packaging, a pyramid or rounded top, or a non-stackable instruction on the bill of lading, ODFL and Saia may apply a height of at least 96 in. A 48 × 40 in pallet at 500 lb then goes from 53.33 to 106.67 cubic feet, from 9.4 to 4.69 lb/ft³, and from class 100 to class 175.
What is the difference between freight density and dimensional weight?
LTL carriers usually price by density, while parcel carriers use dimensional weight (DIM weight). DIM weight divides L × W × H by a carrier's DIM factor, for example 139 cubic inches per pound for UPS Daily Rates, and the carrier bills whichever is greater, DIM weight or actual weight.
How do I convert lb/ft³ to kg/m³?
Multiply by 16.01846, since 1 lb/ft³ equals 16.01846 kg/m³. A pallet at 9.4 lb/ft³ is about 150 kg/m³. The calculator shows both values side by side, but the NMFC class scale is set in lb/ft³.
Sources
- NMFTA — National Motor Freight Classification (NMFC) overview
- NMFTA — Major NMFC changes taking effect in 2025 (density-based classification)
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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