Understanding Freight Classes: NMFC Codes Explained for Truckers

What Are Freight Classes and Why Do They Matter?

The National Motor Freight Traffic Association (NMFTA) created a system of 18 freight classes, numbered from 50 to 500, to standardize how LTL (Less-Than-Truckload) shipments are priced. Each class is based on four factors: density (weight per cubic foot), stowability (how easily the freight can be stored with other items), handling difficulty, and liability (the value and fragility of the goods).

Class 50 is the lowest classification, assigned to the densest, easiest-to-handle freight like clean brick, sand, or nuts and bolts. Class 500 is the highest, assigned to items like bags of gold dust, live animals, or valuable antiques. The higher the class number, the more expensive it is to ship per pound because the freight takes up more space relative to its weight, requires special handling, or carries higher risk.

While freight classes primarily affect LTL pricing, they matter for truckload carriers too. Understanding freight classes helps you evaluate whether a load is appropriately priced. A full truckload of Class 50 freight (dense, heavy) means you are likely maxing out your weight limit at 43,000 to 45,000 pounds. A full truckload of Class 250 freight might only weigh 10,000 pounds but fill every cubic inch of your trailer. The rate per mile should reflect this difference.

Every commodity has an NMFC (National Motor Freight Classification) code that determines its freight class. These codes are maintained in the NMFC database, which is updated regularly. Knowing the NMFC code for the freight you are hauling helps you verify that bills of lading are accurate and that you are not being asked to haul misclassified freight that could create liability issues.

The 18 Freight Classes Explained

Class 50 (over 50 lbs per cubic foot): The densest freight. Examples include durable metal items, bags of cement, flour in sacks, and bricks. This is the cheapest freight to ship because it is dense, easy to handle, and low risk.

Class 55 to Class 77.5: Moderately dense freight. Class 55 includes hardwood flooring, bricks in crates, and cement in bags. Class 60 covers car accessories and bottled beverages. Class 65 includes car parts, bottled water, and canned goods. Class 70 covers food items, automobile engines, and newspapers. Class 77.5 includes tires, bathroom fixtures, and some machinery.

Class 85 to Class 110: Medium-density freight that requires more care. Class 85 covers crated machinery and transmissions. Class 92.5 includes computers, monitors, and refrigerators. Class 100 covers boat covers, wine cases, and canvas. Class 110 includes cabinets, framed artwork, and table saws.

Class 125 to Class 175: Lower-density items requiring careful handling. Class 125 covers small household appliances and vending machines. Class 150 includes auto sheet metal, bookcases, and ATV covers. Class 175 covers clothing, couches, and stuffed furniture.

Class 200 to Class 500: The lowest-density, highest-value, or most difficult-to-handle freight. Class 200 includes auto sheet metal parts and aluminum tables. Class 250 covers bamboo furniture and mattresses. Class 300 includes model boats, chairs, and wood cabinets. Class 400 covers deer antlers and live plants. Class 500 is reserved for extremely high-value or unusual items like bags of gold dust, live animals, or priceless artwork.

How to Calculate Freight Density and Determine Class

Freight density is the most important factor in classification. To calculate density, divide the weight of the shipment by its volume in cubic feet. For example, a pallet that weighs 500 pounds and measures 48 inches long by 40 inches wide by 48 inches high has a volume of 53.3 cubic feet (48 x 40 x 48 = 92,160 cubic inches, divided by 1,728 cubic inches per cubic foot). The density is 500 divided by 53.3, which equals 9.38 pounds per cubic foot. This density falls into Class 100.

Many shippers and brokers use freight density calculators to determine the class, and you should know how to verify their work. An incorrect freight class on a bill of lading can result in reclassification charges, additional fees, or disputes between the shipper and carrier. If you show up to pick up what is described as Class 70 freight and find that the pallets are much larger and lighter than expected, you may be hauling Class 150 freight that should command a higher rate.

The four classification factors interact with each other. A shipment might be moderately dense but classified higher due to handling requirements (like a crated glass table that needs careful loading) or liability risk (like electronics that are easily damaged and expensive to replace). Stowability refers to whether the freight can be loaded next to or on top of other shipments. Hazardous materials, for instance, cannot be stored next to food products, which limits stowability and can increase the classification.

Familiarity with common freight classes in your niche helps you quickly evaluate loads. If you haul a lot of beverages (Class 60-70), canned goods (Class 65), or building materials (Class 50-85), you know the typical density and weight per pallet, which helps you estimate whether a load will max out on weight or space.

How Freight Class Affects Your Rates and Revenue

For LTL carriers, freight class directly determines the per-hundredweight rate charged to the shipper. Higher classes mean higher rates per pound but lower total weight per shipment. For truckload carriers, the relationship is less direct but still important.

When a broker posts a load, the rate should reflect the freight's density and handling requirements. A 44,000-pound truckload of Class 50 freight (dense metal parts) pays differently than a 15,000-pound truckload of Class 200 freight (lightweight furniture) even if both fill a 53-foot trailer. The heavy load means more wear on your truck and tires, higher fuel consumption, and more weight station scrutiny. The light load means less weight-related wear but you are hauling a lot of air.

Understanding class helps you spot underpriced loads. If a broker offers a load described as 42,000 pounds of Class 55 freight at $1.80 per mile, that is a heavy, dense load that should be closer to $2.20 to $2.50 per mile given the weight. Conversely, a 12,000-pound load of Class 175 freight (filling the entire trailer with lightweight goods) might look low-paying but involves minimal weight stress on your equipment.

Some of the most profitable loads for owner-operators are high-class, lightweight freight. A trailer full of Class 200+ freight weighs relatively little, causes less tire and brake wear, improves your fuel efficiency, and often pays well because the shipper is accustomed to higher transportation costs for their product category. Specialty carriers who focus on high-class freight like furniture, electronics, or trade show exhibits often command premium rates.

Bills of Lading and Freight Classification Accuracy

The bill of lading (BOL) is the legal document that describes the freight being transported, including its NMFC code, freight class, weight, and piece count. As the carrier, you are responsible for verifying that the BOL accurately describes what you are picking up. If the freight is misclassified, whether intentionally or by mistake, it can create problems at delivery, with insurance claims, and even at weigh stations.

Common BOL classification errors include understating the freight class to get a lower shipping rate (the shipper saves money but you may be hauling more delicate or valuable freight without appropriate insurance coverage), overstating the weight (which can put you over legal weight limits), and failing to note hazardous materials or special handling requirements.

When you pick up a load, compare the BOL description to what is actually on the pallets or in the crates. If the BOL says 20 pallets of Class 65 canned goods at 40,000 pounds, but you see 20 pallets of lightweight boxed electronics, something is wrong. Do not sign the BOL until discrepancies are resolved. Annotate the BOL with any differences you observe, such as damaged packaging, wrong piece count, or freight that does not match the description.

Keep copies of every BOL for at least one year. In the event of a freight claim, the BOL is the primary document used to determine liability. If the freight was improperly classified on the BOL and a claim arises, the classification information becomes critical in determining who is responsible.

Practical Tips for Working With Freight Classes

Learn the freight classes for the commodities you commonly haul. If you specialize in food and beverage freight, know that bottled beverages are typically Class 60, canned goods are Class 65, frozen food is Class 70-85, and fresh produce varies by type and packaging. This knowledge helps you evaluate loads quickly and spot discrepancies.

Use the NMFC database (available through the NMFTA for a subscription fee) or free online freight class calculators to look up specific commodities. Many load boards and TMS platforms include freight class information in load postings, though this information is only as accurate as what the shipper provided.

When negotiating rates, factor in the freight class. Do not accept the same rate per mile for a 44,000-pound load as for a 15,000-pound load. The heavy load costs more in fuel, creates more wear on your equipment, and limits your ability to carry additional stops. Calculate your cost per mile based on actual weight, not just distance.

For mixed-class loads (different commodities on the same trailer), the highest class in the load typically determines the overall classification for LTL purposes. For truckload, evaluate each commodity separately and ensure your insurance coverage is appropriate for the most valuable item on the trailer. If you are hauling a mixed load that includes high-value electronics alongside general merchandise, make sure your cargo insurance covers the electronics value.