If you've ever shipped LTL freight and wondered why rates vary so widely for seemingly similar shipments, freight class is usually the answer. Understanding NMFC freight classification is one of the most important things a shipper can learn — it directly controls how much you pay on every LTL shipment.
What Is Freight Class?
Freight class is a standardized commodity classification system developed by the National Motor Freight Traffic Association (NMFTA) and codified in the National Motor Freight Classification (NMFC) directory. All LTL carriers use freight class to set rates.
Classes range from Class 50 (the densest, least expensive freight) to Class 500 (the least dense, most expensive). The higher your freight class, the higher your LTL rate.
What Determines Freight Class?
Freight class is determined by four factors:
- Density — Weight relative to size (lbs per cubic foot). This is the most important factor. Denser freight = lower class = lower rate.
- Stowability — Can the freight be loaded with other goods without difficulty? Irregularly shaped or oversized items may get a higher class.
- Handling — Is the freight easy to handle mechanically, or does it require special care? Fragile or difficult-to-handle items get a higher class.
- Liability — What is the likelihood of damage, theft, or damage to other freight? High-value or perishable goods carry higher liability and higher class.
NMFC Freight Class Chart
| Class | Weight per Cubic Foot | Examples | Rate Level |
|---|---|---|---|
| 50 | 50+ lbs/cu ft | Bricks, sand, steel beams, hardwood floors | Lowest |
| 55 | 35–50 lbs/cu ft | Construction materials, motors, car parts | Very Low |
| 65 | 22.5–35 lbs/cu ft | Auto parts, machinery, bottled beverages | Low |
| 70 | 15–22.5 lbs/cu ft | Tires, engine parts, aluminum wire | Low-Moderate |
| 77.5 | 13.5–15 lbs/cu ft | Brake parts, cable in boxes, clothing | Moderate |
| 85 | 12–13.5 lbs/cu ft | Crated machinery, cast iron stoves | Moderate |
| 92.5 | 10.5–12 lbs/cu ft | Computers, refrigerators, monitors | Moderate-High |
| 100 | 9–10.5 lbs/cu ft | Boat covers, car covers, canvas | High |
| 110 | 8–9 lbs/cu ft | Cabinets, framed artwork, table saws | High |
| 125 | 7–8 lbs/cu ft | Small appliances, book cases, vending machines | Very High |
| 150 | 6–7 lbs/cu ft | Auto sheet metal, bookcases, engine hoods | Very High |
| 175 | 5–6 lbs/cu ft | Clothing in boxes, couches, stuffed furniture | Premium |
| 200 | 4–5 lbs/cu ft | Auto sheet metal parts, aircraft parts, aluminum table | Premium |
| 250 | 3–4 lbs/cu ft | Bamboo furniture, mattresses, plasma TVs | Very Premium |
| 300 | 2–3 lbs/cu ft | Wood cabinets, ping pong tables, model boats | Highest Range |
| 400 | 1–2 lbs/cu ft | Deer antlers, ping pong balls | Highest Range |
| 500 | Less than 1 lb/cu ft | Gold dust, bags of air, low-density foam | Highest |
How to Calculate Your Freight's Density
Density is the key driver of freight class. Here's how to calculate it:
- Measure your shipment — Length × Width × Height in inches
- Convert to cubic feet — (L × W × H) ÷ 1,728
- Divide weight by cubic feet — Actual weight (lbs) ÷ cubic feet = density (lbs/cu ft)
- Match density to freight class — Use the NMFC class chart above
Example: A shipment measuring 48" × 40" × 48" and weighing 500 lbs:
Volume = (48 × 40 × 48) ÷ 1,728 = 53.3 cubic feet
Density = 500 ÷ 53.3 = 9.4 lbs/cu ft → Class 92.5
Density-Based vs. Commodity-Based Classification
Some freight is classified by density (you calculate the class based on the formula above), while other commodities have a fixed NMFC class regardless of density. The NMFC directory lists thousands of specific commodities with their assigned classes.
When in doubt, use the density method as a starting point, but verify your specific commodity in the NMFC guide or ask your freight broker to confirm.
Avoiding Reclassification Charges
Reclassification happens when a carrier inspects your freight at a terminal and determines you used an incorrect (lower) freight class. The consequences:
- The shipment is reclassified to the correct (higher) class
- You're billed the difference plus an inspection fee (typically $50–$150)
- Delivery may be delayed during the inspection process
To avoid reclassification: always measure accurately, don't understate weight, and verify your NMFC code before booking. Your freight broker can help you confirm the correct class before every shipment.
Not sure about your freight class? MyExpressFreight's logistics team will help you classify your shipment correctly and find the most competitive LTL rate across our 500+ carrier network.
Get an LTL Quote →When to Consider FTL Instead of LTL
If your freight class is high (100+), your LTL rates can become surprisingly expensive. At that point, it's worth comparing full truckload (FTL) rates, which are not affected by freight class. For high-class freight over 8,000–10,000 lbs, FTL is often more cost-effective even if you don't fill the truck.
FAQs About Freight Class
What is freight class?
Freight class is a standardized system (NMFC) that LTL carriers use to set rates. Classes range from 50 (densest, lowest rate) to 500 (least dense, highest rate), determined by density, stowability, handling, and liability.
How do I determine my freight class?
Calculate your freight's density (weight ÷ cubic feet). Match the density to the NMFC class chart. For specific commodities, check the NMFC directory or ask your freight broker to confirm the correct class.
What happens if I use the wrong freight class?
Carriers will reclassify your freight at a terminal and charge you the correct rate plus an inspection fee. Always ensure your class is accurate before booking to avoid costly surprises.
Does freight class apply to FTL shipments?
No. Freight class only applies to LTL (Less Than Truckload) shipments. FTL pricing is based on lane mileage and market rates, not freight class — which is one reason FTL can be more predictable for high-class commodities.