Freight class determines what you pay for every LTL shipment, and getting it wrong is expensive in both directions: overstate it and you overpay on every load, understate it and the carrier reclasses the shipment and bills you the difference plus an inspection fee. The good news — since the NMFC's July 2025 overhaul, calculating class is a clean four-step density exercise for most freight.
Step 1 — Measure the handling unit at its extremes
Measure length × width × height in inches of each handling unit exactly as it ships: pallet included, packaging included, and measured at the widest points. If cartons overhang the pallet by an inch, that inch counts. If the shrink-wrap bulges, the bulge counts. Carriers' dimensioner machines measure the extreme cuboid, so you should too.
Step 2 — Convert to cubic feet
Multiply the three dimensions to get cubic inches, then divide by 1,728 (the cubic inches in a cubic foot):
48 × 40 × 48 = 92,160 in³ → 92,160 ÷ 1,728 = 53.33 ft³
Step 3 — Divide weight by cube to get density
Weigh the complete handling unit (a forklift scale or floor scale — bathroom-scale arithmetic is how reclass fees happen) and divide pounds by cubic feet:
500 ÷ 53.33 = 9.38 lb/ft³
Step 4 — Look the density up in the NMFC table
Find the density band in the current 13-tier scale (effective July 19, 2025):
| Density (lb/ft³) | Freight class |
|---|---|
| Less than 1 | 400 |
| 1 but less than 2 | 300 |
| 2 but less than 4 | 250 |
| 4 but less than 6 | 175 |
| 6 but less than 8 | 125 |
| 8 but less than 10 | 100 |
| 10 but less than 12 | 92.5 |
| 12 but less than 15 | 85 |
| 15 but less than 22.5 | 70 |
| 22.5 but less than 30 | 65 |
| 30 but less than 35 | 60 |
| 35 but less than 50 | 55 |
| 50 or greater | 50 |
9.38 lb/ft³ falls in “8 but less than 10” → class 100. That's the estimated class for the BOL, assuming the commodity sits on the NMFC's standard density scale (most general freight now does — see what changed in 2025). Commodities with special handling, stowability or liability provisions keep commodity-specific classes regardless of density.
Multiple pallets: pool, don't average
For a multi-pallet shipment, carriers compute one density for the whole shipment: total weight ÷ total cubic feet.
- Pallet A: 48 × 40 × 60 in = 66.67 ft³ at 400 lb
- Pallet B: 48 × 40 × 36 in = 40 ft³ at 700 lb
- Pooled: 1,100 lb ÷ 106.67 ft³ = 10.31 lb/ft³ → class 92.5
Averaging the per-pallet classes (A alone is 6 lb/ft³ → 125; B alone is 17.5 → 70) gives a nonsense answer that matches nothing on the invoice. Pool the math — or add rows in the calculator and it pools automatically.
The five mistakes that trigger reclass fees
- Forgetting the pallet. 5.5 in of pallet height on a 48-in load is ~10% of the cube.
- Measuring the box, not the bulge. Dimensioners see the extremes.
- Rounding density before the lookup. 9.98 is class 100; “about 10” is not.
- Using a pre-2025 chart. Classes 77.5, 110, 150, 200 and 500 no longer exist on the density scale — a June 2025 cheat sheet now misquotes real freight.
- Ignoring the commodity item. Density is the default, not the override; NMFC items with special provisions still win.