Freight density calculator
Enter length, width, height, and weight to see the density and the density-based class.
Density
— lb/ft³
- Volume
- — ft³
- Freight class
- —
- Subprovision
- —
This is a density-based estimate using the 13-subprovision density scale from NMFC Docket NMFC-2025-1. Actual classification is also affected by handling, stowability, and liability characteristics, and the density scale applies only when those issues are absent. Your carrier makes the final call.
| Sub | Density (lb/ft³), as published | Class |
|---|---|---|
| 1 | Less than 1 | 400 |
| 2 | 1 but less than 2 | 300 |
| 3 | 2 but less than 4 | 250 |
| 4 | 4 but less than 6 | 175 |
| 5 | 6 but less than 8 | 125 |
| 6 | 8 but less than 10 | 100 |
| 7 | 10 but less than 12 | 92.5 |
| 8 | 12 but less than 15 | 85 |
| 9 | 15 but less than 22.5 | 70 |
| 10 | 22.5 but less than 30 | 65 |
| 11 | 30 but less than 35 | 60 |
| 12 | 35 but less than 50 | 55 |
| 13 | 50 or greater | 50 |
Enter the length, width, height, and weight of a shipment to get its volume in cubic feet and its density in pounds per cubic foot — the figure the NMFC density scale is keyed on. The calculation is the same one behind this site's freight class calculator, but this page answers the density question directly: what the number means, how to measure a shipment so that it is right, and where density stops being the answer.
What density measures
Density is weight divided by volume. Volume is the three dimensions multiplied together, so density answers a single question: for the space this shipment takes up, how much does it weigh?
The unit is pounds per cubic foot, written lb/ft³ and also called PCF in freight documentation. A dense shipment packs a lot of weight into a small space; a light, bulky one does the opposite.
Because density is a ratio, it is the one figure that does not change when the same freight is described in different dimensions. That is why the NMFC density scale is keyed on it rather than on weight or volume alone.
Measure the handling unit, not the product
Measure what you actually tender: the pallet, the overhang, the shrink wrap, and any packaging. A product's nominal dimensions and its shipped dimensions are usually not the same, and the difference goes straight into the density.
This is the most common way a density comes out wrong. A pallet that overhangs its footprint by a couple of inches, or a stack that is not quite square, changes the volume by more than most people expect — volume moves with the cube, so an error in any one dimension is an error in the result.
Height is the dimension most often estimated rather than measured, and on a stacked shipment it is also the one that changes most between pick-up and delivery. If the density is close to a boundary, the height is worth re-checking before the number is used for anything.
Density is not dimensional weight
These two figures are computed from the same three dimensions and they answer opposite questions, which is why they are so often confused.
Density is weight divided by volume. It goes up when freight is heavy for its size, and it is what classification scales are keyed on.
Dimensional weight is volume divided by a divisor the carrier sets. It goes up when freight is light for its size, and it is a pricing construct: when a shipment is bulky enough that its dimensional weight exceeds its actual weight, the carrier bills on the dimensional figure.
So the same shipment can have a high density and be billed on actual weight, or a low density and be billed on dimensional weight. A density calculator does not tell you which — that depends on your carrier's rules.
Several handling units in one shipment
When a shipment is made up of more than one unit, its density is the total weight divided by the total volume. Add the weights, add the volumes, then divide once.
Averaging the units' individual densities is the tempting shortcut and it is wrong whenever the units are different sizes: a small, heavy unit and a large, light one do not contribute equally to the shipment, but a plain average would treat them as if they did.
This calculator takes one unit's dimensions. For a multi-unit shipment, work out the total weight and total volume first, then enter a single equivalent shape — the density is what the arithmetic produces, not what any one unit looks like.
Where density stops being the answer
A density is an input, not a classification. Whether the density scale applies to a given shipment at all depends on the freight's handling, stowability, and liability characteristics, and on NMFC Item (Rule) 170.
That boundary belongs to the classification question rather than to this one, so it is explained in full — along with how the density bands are read and where their edges fall — on the freight class calculator page.
Frequently asked
Is density the same as PCF?
Yes. PCF stands for pounds per cubic foot, which is the same thing as lb/ft³. Freight documents use both, and a density written as "7.97 PCF" and "7.97 lb/ft³" is one figure, not two.
Should I measure the product or the pallet?
The pallet — that is, whatever you actually hand over. Include the pallet itself, any overhang, and the packaging. Measuring the product's nominal dimensions will give a density that is too high, because the space the shipment occupies is larger than the space the product occupies.
Why is my density different from the one on the carrier's paperwork?
Usually because the dimensions are not the ones you measured: carriers re-measure freight, and they measure it as it is tendered rather than as it was packed. Rounding and unit differences account for the rest. If the gap is large, compare the dimensions before comparing the arithmetic.
Does a high density mean a lower freight class?
Under the NMFC density scale, denser freight sits in a lower class number, and lower class numbers generally rate lower. But the class also depends on whether the density scale applies at all, and your carrier's tariff is what decides the price.