Freight density calculator
Freight density is how much a shipment weighs for the space it takes: pounds divided by cubic feet. Enter the length, width, height and weight of each handling unit in inches or centimeters. The calculator gives density in pounds per cubic foot and kilograms per cubic meter, plus the freight class that density falls into on NMFTA’s 2025 scale.
Updated October 12, 2026
Class estimate on NMFTA’s standard 13-sub density scale, in effect since July 19, 2025. The NMFC item for your product sets the class, and some items carry fixed classes for handling, stowability or liability. Confirm in NMFTA’s ClassIT+ or with your carrier.
The freight density formula
Density (lb/ft³) = weight in pounds ÷ cubic feet, where cubic feet = length × width × height in inches ÷ 1,728.
In metric, density in kg/m³ = weight in kilograms ÷ cubic meters. To convert, 1 lb/ft³ is 16.02 kg/m³, and 1 cubic meter is 35.31 cubic feet.
Density for a shipment with several units
Add the weight of every unit, add the cubic feet of every unit, then divide the total weight by the total cubic feet. Do not average the units’ densities: a light, bulky unit and a small, heavy one would be weighted wrongly. The calculator shows the shipment’s density and each unit’s density, so you can see which unit pulls the class up.
From density to freight class
For density-based items, NMFTA’s 13-sub scale turns density into class. A few reference points from the scale: under 1 lb/ft³ is class 400, 8 but less than 10 is class 100, 15 but less than 22.5 is class 70, and 50 or greater is class 50. The full table is on the freight class calculator page.
Worked examples
One pallet
A pallet 48 × 40 × 48 inches at 500 pounds is 53.33 cubic feet. 500 ÷ 53.33 = 9.38 lb/ft³, or 150.2 kg/m³.
Two crates in metric
Two crates of 120 × 100 × 150 cm at 350 kg each take 3.6 cubic meters (127.13 cubic feet) and weigh 1,543.2 pounds in total. 1,543.2 ÷ 127.13 = 12.14 lb/ft³, or 194.4 kg/m³.
How to measure for an accurate density
Measure at the longest points of the handling unit, down to the inch.
Include the pallet, the crate and any packaging. Tick “My measurements do not include the pallet” if your numbers are for the freight alone.
Weigh the unit as it ships, pallet included.
Measure irregular freight carefully. Straight length × width × height can misstate the space a curved or contoured item takes.
Measure the freight that is shipping, not dimensions copied from an old record.
These points follow NMFTA’s own guidance on density mistakes.
Frequently asked questions
What is a good freight density?
Higher density means a lower class and usually a lower rate per pound. On the 2025 scale, freight at 15 lb/ft³ or more rates class 70 or lower, and 50 lb/ft³ or more rates class 50, if the item is density-based.
How do I raise my freight density?
Take empty space out of the unit: use cartons sized to the product, stack cartons squarely on the pallet, and avoid a pallet larger than the load. The weight stays the same while the cubic feet go down.
How do I convert lb/ft³ to kg/m³?
Multiply by 16.02. For example, 10 lb/ft³ is 160.2 kg/m³. To go the other way, divide kg/m³ by 16.02.
Is density the only thing that sets freight class?
No. NMFTA names four characteristics: density, handling, stowability and liability. Many NMFC items are classed by density, but an item can carry its own class for freight that is hard to handle, hard to stow or high in liability.
Related calculators
Freight class calculator: the full 2025 class chart and the gap to the next class.
Pallet calculator: build the pallet, then see its density.
Dimensional weight calculator: the parcel version of the same idea.
A dense pallet still ships late if the parts are late.
Shipping late because a supplier slipped? Morsa, an AI COO for operations, chases open purchase orders with your suppliers in email, Teams, WhatsApp or whatever you already run on, and tells you early when a delivery date will move.
