Freight class, density, and the reweigh

If you ship LTL and your invoices sometimes arrive higher than your quotes, this is almost certainly why. Not fuel, not accessorials. Classification.

What class is

LTL pricing runs on a classification system that sorts commodities into classes roughly from 50 to 500. Low class is cheap to ship. High class is expensive. The class is driven mostly by density — pounds per cubic foot — with adjustments for how easily the freight is handled, how likely it is to be damaged, and how much liability it carries.

The logic is sound. A trailer runs out of space long before it runs out of weight. Freight that is light and bulky consumes the scarce resource, so it costs more.

Density, concretely

Density is your shipment's weight divided by its cubic footage — and the cube must include the pallet and any overhang, not just the product.

A standard 48×40 pallet stacked 48 inches high occupies about 53 cubic feet. Put 600 pounds on it and you are near 11 lbs per cubic foot. Put 1,200 pounds on the same footprint and you are near 22. Those are meaningfully different classes and meaningfully different rates, for freight that looks identical sitting on the dock.

The reweigh

Carriers inspect. Terminals have scales and increasingly have dimensioning equipment that measures a pallet automatically as it moves through. If your declared weight, dimensions, or class do not match what they measure, they reclassify and rebill.

That correction arrives well after delivery, often weeks later, and it is not a negotiation. It is a measurement. This is why the invoice does not match the quote.

Estimates that cause it:

• "About 500 pounds" when it is 640.
• Product dimensions used instead of palletized dimensions.
• Height measured to the top of the box, ignoring the pallet.
• Overhang not counted — if it hangs over, it takes the space.
• Shrink wrap and dunnage left out of the weight.

Getting it right

1. Measure and weigh as shipped. Palletized, wrapped, ready to go.
2. Keep it on the SKU record. Class, dimensions, weight, and the density you calculated.
3. Re-check when packaging changes. New pallet size or new box spec changes the density and can change the class.
4. Describe the commodity accurately. Vague descriptions get classified conservatively, which means expensively.
5. If you are reclassified, ask for the evidence. A legitimate reweigh comes with a certificate or inspection record showing measured weight and dimensions. Ask for it. Carriers who are right will produce it. If nobody can produce it, dispute it.

Density Based Rating

Much of the industry has moved toward density-based rating, which prices directly on measured density rather than a traditional class lookup. It removes some judgment from the process and can benefit shippers whose freight is denser than their class implied.

It also raises the stakes on measurement accuracy, because the price now keys directly off numbers you provided. Everything above matters more under density-based rating, not less.

None of this is exotic. It is a tape measure, a scale, and a spreadsheet column. It is genuinely one of the highest-return hours you can spend on a freight program.

Next: Accessorials you can prevent →