Worked example
A two-pallet shipment where the pallets are nothing alike.
- Pallet one: 48 × 40 × 50 inches at 600 pounds. That is 55.56 ft³ and 10.80 lb/ft³, which on its own would be class 92.5.
- Pallet two: 48 × 40 × 48 inches at 1,500 pounds. That is 53.33 ft³ and 28.12 lb/ft³, which on its own would be class 65.
- Together: 108.89 ft³ and 2,100 pounds, so 19.29 lb/ft³ — class 70.
Neither pallet is class 70. The combined figure lands between them, which is why you cannot average the two classes and why rating a mixed shipment off its largest piece is guesswork.
The formula
Piece volume = L × W × H ÷ 1,728, × quantity Total volume = sum of every piece volume Total weight = sum of every piece weight Density = total weight ÷ total volume Class = the NMFC band that density falls in
Density is a ratio, so it has to be computed once over the totals. Averaging the per-piece densities gives a different and wrong answer whenever the pieces differ in size.
When pieces are rated separately
Whether a carrier rates the shipment as a whole or piece by piece depends on the bill of lading and the tariff. Many LTL carriers rate the shipment; some rate each handling unit, which can cost more when one pallet is much lighter than the rest.
This calculator gives you both views: the combined class in the result panel, and each piece own density and class on its card. If your carrier rates by piece, read the cards. If it rates the shipment, read the headline.
Where a mixed shipment loses money
The expensive pattern is one light, bulky pallet travelling with several dense ones. It drags the combined density down, and because the bands are uneven at the light end, it can cost a class or two across the whole shipment.
Two fixes are usually available. The first is to redistribute: if the bulky pallet has empty space and the dense ones have spare weight capacity, moving product between them evens out the density without changing what ships. The second is to split the bill of lading, so the light pallet is rated separately and does not pull the rest down with it. Whether that helps depends on your carrier — two bills can mean two minimum charges.
Run both through this calculator before you decide. Enter the combined shipment, then enter the dense pallets alone, and compare the classes. The difference tells you whether splitting is worth the extra minimum.
Common mistakes
- Averaging the classes. Class is not linear and density is a ratio. Add the volumes and the weights, then divide once.
- Entering weight per shipment in a per-piece field. Each row takes the weight of one piece, multiplied by the quantity on that row.
- Leaving out pallets and packaging. They count toward both the volume and the weight, and they usually raise the density slightly.
- Mixing units between rows. Set the toggle once; every row uses the same system.
- Assuming a denser pallet always helps. It helps the combined density, but if the carrier rates by piece, the light pallet still carries its own high class.
FAQ
How do I calculate freight density?
Divide total weight in pounds by total volume in cubic feet. For a mixed shipment, add up every piece volume and every piece weight first, then divide once.
Why does the combined class differ from the individual pieces?
Because density is a ratio, not an average. A heavy dense pallet and a light bulky one combine into a shipment whose density sits between them, and the class follows that combined figure.
Should each pallet be rated separately?
That depends on the carrier and the bill of lading. Many carriers rate the shipment as a whole, but some rate each handling unit. Ask before you assume the combined figure is what you will be billed on.
What density do I need for a good class?
Class drops as density rises. At 10 lb per cubic foot you are at class 92.5, at 15 you reach class 70, and at 30 you reach class 60. Packing tighter is often the cheapest rate reduction available.
Does packaging count toward the weight?
Yes. Weigh the handling unit exactly as the carrier will: pallet, wrap, dunnage and all.
Rules last checked: Sep 24, 2026
Estimate only. Confirm with your carrier before booking.