Freight class is a standardized rating system used by LTL carriers to price shipments. It determines how much you pay per hundred pounds of freight. Getting the class wrong means reclassification fees, invoice adjustments, or delayed delivery.
The National Motor Freight Classification (NMFC) system assigns every commodity a freight class between 50 and 500. Lower classes are cheaper to ship. Higher classes cost more. Understanding how class is determined helps you avoid billing surprises.
The 18 Freight Classes
| Class | Typical Density | Examples |
|---|---|---|
| 50 | Over 50 lbs/cubic ft | Bricks, sand, steel bars |
| 55 | 35–50 lbs/cubic ft | Hardwood flooring, sheet glass |
| 65 | 22.5–35 lbs/cubic ft | Car parts, boxed machinery |
| 70 | 15–22.5 lbs/cubic ft | Auto engines, food items |
| 85 | 12–15 lbs/cubic ft | Crated machinery, cast iron |
| 92.5 | 10.5–12 lbs/cubic ft | Computers, refrigerators |
| 100 | 9–10.5 lbs/cubic ft | Boat covers, wine cases |
| 110 | 8–9 lbs/cubic ft | Cabinets, framed pictures |
| 125 | 7–8 lbs/cubic ft | Small household appliances |
| 150 | 6–7 lbs/cubic ft | Auto sheet metal parts |
| 175 | 5–6 lbs/cubic ft | Clothing, couches |
| 200 | 4–5 lbs/cubic ft | Auto sheet metal parts, mattresses |
| 250 | 3–4 lbs/cubic ft | Bamboo furniture, plasma TVs |
| 300 | 2–3 lbs/cubic ft | Wood cabinets, tables |
| 400 | 1–2 lbs/cubic ft | Deer antlers |
| 500 | Under 1 lb/cubic ft | Ping pong balls, gold dust |
How Freight Class Is Determined
NMFC freight class is based on four characteristics:
- Density — weight per cubic foot of the shipment
- Stowability — how easily the freight fits and stacks with other cargo
- Handling — special requirements for loading or unloading
- Liability — susceptibility to damage, theft, or risk to other freight
Density is the most common factor. A shipment that weighs 500 lbs and occupies 10 cubic feet has a density of 50 lbs per cubic foot, which maps to class 50 — the cheapest LTL class.
How to Calculate Freight Density
To calculate density: measure the length, width, and height of the shipment in inches. Multiply them together and divide by 1,728 to get cubic feet. Then divide the total weight by cubic feet.
Example: A shipment measuring 48" × 40" × 48" and weighing 500 lbs has a volume of (48 × 40 × 48) / 1,728 = 53.3 cubic feet. Density = 500 / 53.3 = 9.4 lbs per cubic foot, which maps to class 100.
What Happens If the Class Is Wrong?
Carriers inspect and weigh freight at the terminal. If they determine the stated class does not match the actual freight, they issue a freight bill correction — a reclassification notice with an adjusted charge.
Reclassification charges are not negotiable after delivery. Disputing them requires proof that the original class was correct, including photographs, weight tickets, and commodity documentation.
Density-Based vs Commodity-Based Classification
Some commodities have fixed NMFC classes regardless of density. Others are classified purely on density. When a commodity has a fixed class, you cannot argue that the density suggests a lower class.
For density-based items, accurate measurement pays off directly. A shipment classified at class 92.5 instead of class 100 because of precise measurement can reduce the LTL rate by 10 to 20 percent on some lanes.
Frequently Asked Questions
Do I need to know freight class for FTL shipments?
No. Freight class applies only to LTL shipments. FTL pricing is based on weight, mileage, and lane — not NMFC classification.
What if I don't know the correct class?
Use the NMFC directory or ask your freight broker. SIOX Logistics verifies freight class before booking LTL shipments to avoid reclassification charges.
Can freight class change?
Yes. The NMFC publishes periodic updates. Some commodities move between classes when standards change. Check the classification for products you ship regularly at least once per year.
Need help classifying your freight correctly?
SIOX Logistics reviews freight class on every LTL shipment before booking. Request a freight quote and let us verify the classification before the truck arrives.
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