Class starts as one division: pounds divided by cubic feet. Everything else is refinement.
The calculator
Measure the load as it will be handed over, pallet and wrap included, and give the gross weight for all pieces together. Length times width times height divided by 1,728 gives cubic feet; weight divided by cubic feet gives density.
- Cubic feet
- -
- Density
- -
- Density band
- -
- Estimated class
- -
Density-based estimate only. A specific commodity can carry its own item number in the classification, and a carrier can reweigh or remeasure the shipment at a terminal, so treat this as the number to open a conversation with rather than the number on the invoice.
The bands it reads from
Thirteen density bands, published on the density calculator page of a national LTL carrier and checked 2026-07-28. Read down the table and the pattern is plain: pack more weight into the same trailer space and the class number falls with it.
| Density, lb per cubic foot | Class | Typical freight in this band |
|---|---|---|
| 50 or greater | 50 | Metal stock, castings, dense stone |
| 35 but less than 50 | 55 | Bricks, cement, hardwood flooring |
| 30 but less than 35 | 60 | Boxed vehicle parts |
| 22.5 but less than 30 | 65 | Bottled drinks, canned goods, books |
| 15 but less than 22.5 | 70 | Boxed hardware, small engines |
| 12 but less than 15 | 85 | Crated machinery, tools |
| 10 but less than 12 | 92.5 | Mixed cartons on a pallet |
| 8 but less than 10 | 100 | Boxed appliances, canvas goods |
| 6 but less than 8 | 125 | Small household appliances |
| 4 but less than 6 | 175 | Clothing, assembled furniture |
| 2 but less than 4 | 250 | Bulky light goods, mattresses |
| 1 but less than 2 | 300 | Wood cabinets, tables and chairs |
| Less than 1 | 400 | Very light bulky items |
The examples in the third column are the sort of goods that commonly land in each band; they are guidance for reading the table, not classifications. What governs on an invoice is the item number the classification assigns to your specific commodity.
Three worked examples
Run these through the tool above to check it against your own arithmetic. Each one uses a shipment profile we have actually quoted or measured, and the density figures are plain division from the dimensions and weights shown.
| Shipment | Cubic feet | Density | Class band |
|---|---|---|---|
| 48 x 40 x 48 in pallet, 500 lb | 53.33 | 9.38 lb per cu ft | 100 |
| 48 x 40 x 48 in pallet, 700 lb | 53.33 | 13.13 lb per cu ft | 85 |
| 30 x 24 x 24 in carton, 150 lb | 10.00 | 15.00 lb per cu ft | 70 |
The first two rows are the whole argument for packing tight. Same footprint, same trailer space, two hundred more pounds, and the class drops a band because the trailer is doing more work for the same volume. SMKlog sells parcel labels only.
What density alone will not tell you
Three other characteristics are in play
Density is one of four transportation characteristics in the classification. The others are handling, stowability and liability, defined by the classification authority as how easy the freight is to move across a dock and into or out of a trailer, how effectively it can be stowed in a trailer for transport, and how likely it is to cause damage or be damaged, per nmfta.org, checked 2026-07-28. Fragile, hazardous or awkwardly shaped goods can class above what their density alone suggests.
Your commodity may have its own number
Many commodities carry a specific item number in the classification, and where one exists it governs regardless of what a density calculator says. Treat a density-derived class as the opening position in a quote, and expect the carrier to confirm it against the item that actually applies.
Carriers check the numbers themselves
Terminals reweigh and remeasure freight, and a carrier lists reweighed freight among its published charges. A shipment quoted at a class it does not merit gets corrected after the fact, which is why measuring the wrapped load rather than the bare cartons is worth the extra minute.
Where this fits with what we sell
This tool is here because knowing your class before you ask a freight carrier for a price makes the conversation shorter and the number better. SMKlog sells parcel labels only and does not arrange pallet or freight shipments.
Read the LTL explainer Price a smaller load as a parcel instead See what else moves the price
Freight class questions
How do I calculate freight class?
Multiply length by width by height in inches, divide by 1,728 for cubic feet, then divide the total weight in pounds by that figure to get density. Read the density against the published bands: 8 to 10 lb per cubic foot is class 100, 12 to 15 is class 85, and so on down to class 50 at 50 lb per cubic foot or greater.
What class is a 500 lb pallet?
It depends on the size. A 48 x 40 x 48 in pallet is 53.33 cubic feet, so 500 lb works out at 9.38 lb per cubic foot, which sits in the 8 to 10 band at class 100. Add 200 lb without changing the footprint and density rises to 13.13, moving it to class 85.
Is density the only thing that sets freight class?
No. Handling, stowability and liability sit alongside it, and many commodities carry their own item number in the classification that governs whatever the density works out to. A density calculation is the right opening figure, not the final one.
What is an NMFC code?
It is the item number the national classification assigns to a particular commodity, which tells a carrier how that specific thing is classed. Where an item number applies it overrides a density-only estimate, so a carrier will normally confirm the code as part of quoting.