Working paper
Freight cost, explained by NMFC class
One number decides what an LTL carrier charges you, and it is not weight. It is density — and since 19 July 2025 the link between density and price has been almost mechanical. This page walks one real pallet all the way to an invoice, twice, and shows what the difference is worth.
Density is weight divided by the space it occupies — all of it
Not the volume of your goods. The volume of the envelope the carrier has to load: pallet included, wrap included, anything overhanging included. This is the single most common costing error, and it always goes the expensive way.
1,728 is cubic inches per cubic foot. Everything downstream of this line — the class, the linehaul, the fuel surcharge computed on top of the linehaul — follows from 9.00.
Density maps to class on a published ladder
NMFTA Docket 2025-1 took effect 19 July 2025 and replaced the old eleven-tier density scale with thirteen, adding classes 55 and 50 at the dense end. For any commodity without handling, stowability or liability concerns, class is now read straight off this table.
| Sub | Density, lb per ft³ | Class |
|---|---|---|
| 1 | under 1 | 400 |
| 2 | 1 – 2 | 300 |
| 3 | 2 – 4 | 250 |
| 4 | 4 – 6 | 175 |
| 5 | 6 – 8 | 125 |
| 6 | 8 – 10 | 100 |
| 7 | 10 – 12 | 92.5 |
| 8 | 12 – 15 | 85 |
| 9 | 15 – 22.5 | 70 |
| 10 | 22.5 – 30 | 65 |
| 11 | 30 – 35 | 60 |
| 12 | 35 – 50 | 55 |
| 13 | 50 and above | 50 |
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Source: NMFTA Docket 2025-1, effective 19 July 2025. Grade A — a published classification, not an estimate. Docket 2026-1 followed on 6 February 2026, continuing the consolidation of commodity listings into this same density structure. Items that still carry handling, stowability or liability provisions are classed on those, not on density alone.
Which means your class is really a stack height
Hold the weight and the footprint still, and density is nothing but height. Every class boundary on that ladder becomes a mark on a tape measure — and for this pallet, here is where they fall.
| To be classed | You need | Stack no taller than |
|---|---|---|
| 100 | 8 pcf or denser | 69.8″ or shorter |
| 92.5 | 10 pcf or denser | 55.8″ or shorter |
| 85 | 12 pcf or denser | 46.5″ or shorter |
| 70 | 15 pcf or denser | 37.2″ or shorter |
| 65 | 22.5 pcf or denser | 24.8″ or shorter |
| 60 | 30 pcf or denser | 18.6″ or shorter |
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The invoice, line by line, both ways
Class sets the rate per hundredweight. Weight in hundredweight times that rate is the linehaul. The fuel surcharge is then a percentage of the linehaul — which is why a class error never costs you only the class error.
| Line | As shipped, 62″ | Restacked, 46″ |
|---|---|---|
| Density | 9.00 lb/ft³ | 12.13 lb/ft³ |
| Class | 100 | 85 |
| Billable weight | 6.2 cwt | 6.2 cwt |
| Net rate illustrative, per cwt | $32.50 | $28.50 |
| Linehaul | $201.50 | $176.70 |
| Fuel surcharge 26% of linehaul | $52.39 | $45.94 |
| Invoice | $253.89 | $222.64 |
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What just happened $31.25 on one pallet, 12.3% — and not one thing about the product changed. At ten thousand outbound pallets a year that is $312,480. This is the mechanism behind the figure the audit firms publish: 13.2% of LTL spend recoverable through classification accuracy alone.
Fuel multiplies whatever the class did
The surcharge is levied as a percentage of the linehaul, reset weekly against the DOE national average diesel price. It does not care whether your linehaul was right. It scales it.
What the same class correction is worth on one pallet, at three fuel levels.
The real thing In the twelve months to February 2026 the swing in fuel surcharges alone added more than $5.80 per hundredweight to the average LTL invoice — more than the entire year-on-year increase in all-in rates. Fuel is not a line item you negotiate. It is a multiplier on every other decision you got wrong.
Where rates actually are
Reweigh tolerance is typically the smaller of 200 lb or 5%; reclassification is triggered by weight discrepancies, by a density that does not match the description, or by a missing NMFC number on the bill of lading. Inspection frequency rose after the December 2025 updates moved further commodities onto the density scale. Reclassification runs $50–150 per occurrence and a reweigh $25–40, both grade C; invoice variance on individual bills runs 5–25%.
Why this is the page we wrote first.
Everything above is arithmetic anyone can do — after the pallet is built. The reason it is worth money is that the decisions it prices are all made before anyone knows the density: the carton mix is bought weeks out, the class is declared one to three days before the truck moves, and the pallet gets stacked minutes before it ships. That gap is the whole problem, and closing it is the whole product.
The measured version on a real order book · the regulatory clock, including PPWR · send us a month of order lines and we will run it.