LTL Freight Class Guide: How NMFC Classes Work

If you have ever gotten an LTL freight quote and then received a much higher invoice after delivery, freight class misclassification is likely why. Understanding how NMFC freight classes work - and how to calculate yours correctly - is one of the most impactful things you can do to control freight costs.

What Is Freight Class?

Freight class is a standardized rating system established by the National Motor Freight Traffic Association (NMFTA) and defined in the National Motor Freight Classification (NMFC). Classes range from 50 to 500 and are assigned to every type of commodity shipped by LTL (less-than-truckload) carriers.

Your freight class directly determines your LTL rate. Lower class numbers mean lower rates. Class 50 freight is the cheapest to ship. Class 500 freight is the most expensive - often 8-10x higher than Class 50 rates for the same weight.

How Freight Class Is Determined

Most freight is classified primarily by density - weight per cubic foot. The denser your shipment, the lower the class and the lower the rate. This reflects the reality that dense freight is easier for carriers to stack, maximizes trailer space efficiency, and poses less damage risk.

The density formula:

• Calculate cubic feet: (Length × Width × Height in inches) ÷ 1,728
• Calculate density: Total weight in lbs ÷ cubic feet

For example: a pallet that measures 48 × 40 × 48 inches and weighs 500 lbs.

• Cubic feet: (48 × 40 × 48) ÷ 1,728 = 53.3 cubic feet
• Density: 500 ÷ 53.3 = 9.38 lbs per cubic foot
• Freight class: Class 92.5

The 18 NMFC Freight Classes

• Class 50 - over 50 lbs/cu ft: Cement, sand, heavy machinery parts
• Class 55 - 35-50 lbs/cu ft: Bricks, mortar, hardwood flooring
• Class 60 - 30-35 lbs/cu ft: Car parts, steel cables
• Class 65 - 22.5-30 lbs/cu ft: Auto parts, assembled furniture, books
• Class 70 - 15-22.5 lbs/cu ft: Food items, auto engines, unassembled furniture
• Class 77.5 - 13.5-15 lbs/cu ft: Tires, bathroom fixtures
• Class 85 - 12-13.5 lbs/cu ft: Crated machinery, cast iron stoves
• Class 92.5 - 10.5-12 lbs/cu ft: Computers, monitors, refrigerators
• Class 100 - 9-10.5 lbs/cu ft: Boat covers, wine cases, caskets
• Class 110 - 8-9 lbs/cu ft: Cabinets, framed artwork, table saws
• Class 125 - 7-8 lbs/cu ft: Small home appliances
• Class 150 - 6-7 lbs/cu ft: Auto sheet metal, bookcases
• Class 175 - 5-6 lbs/cu ft: Clothing, stuffed furniture
• Class 200 - 4-5 lbs/cu ft: Sheet metal parts, aluminum tables
• Class 250 - 3-4 lbs/cu ft: Mattresses, bamboo furniture, plasma TVs
• Class 300 - 2-3 lbs/cu ft: Wood cabinets, model boats, assembled chairs
• Class 400 - 1-2 lbs/cu ft: Deer antlers, ping pong balls
• Class 500 - under 1 lb/cu ft: Low-density, high-value, or difficult-to-handle commodities

What Misclassification Costs You

If you declare the wrong freight class, the carrier will re-weigh and re-measure your shipment at delivery and issue a classification correction invoice. These are common, often arrive weeks after delivery, and can significantly increase your freight bill.

A shipment billed at Class 70 that a carrier reclassifies to Class 100 can result in a 30-50% higher invoice. At $800 for the original quote, that is a $240-400 surprise charge. Multiply that across regular shipments and misclassification becomes a serious cost problem.

Tips for Getting Freight Class Right

• Always measure the full pallet, including overhang. Carriers measure to the outermost edge of the freight, not the pallet footprint.
• Include all packaging weight. Pallet weight, strapping, and wrapping all count toward the total shipment weight.
• Look up your NMFC item number. Some commodities have specific NMFC classifications that override the density-based system. Check the NMFC directory or ask your freight broker.
• When in doubt, classify higher. It is better to slightly overpay upfront than to receive a reclassification invoice later.

Density-Based vs. Commodity-Based Classification

Not every freight class is determined purely by density. Some commodities have specific NMFC item numbers with set classes that apply regardless of density. This is common for regulated or specialized goods - chemicals, food products, medical equipment, and certain consumer goods all have specific NMFC designations.

If your product has an NMFC item number, that class applies even if the density-based calculation would produce a different class. You can look up NMFC item numbers through the NMFTA website (nmfta.org) or ask your freight broker to do the lookup for you. Getting this wrong is a common source of reclassification charges.

How Carriers Verify Your Freight Class

LTL carriers use a combination of driver visual inspection and automated dimensioning systems at their terminals to verify shipment dimensions and weight. When a shipment arrives at the carrier's origin terminal, a dock worker will often check that the description and dimensions match what was booked.

At the destination terminal, many carriers now use automated dimensioning tunnels that measure every pallet as it moves through the facility. These systems catch misclassifications that manual inspection might miss. If the carrier's measurement differs from your declared dimensions, they will issue a correction invoice - sometimes called a freight bill correction or a weight and inspection charge.

Keep your packing slips and original dimensions on file. If you receive a reclassification invoice you believe is wrong, you have the right to dispute it - but you need documentation of the original dimensions and weight to make the case.

Reducing LTL Costs Through Better Classification

The single most impactful way to reduce LTL costs is to increase shipment density. More weight in less space means a lower freight class and a lower rate. Practical approaches:

• Palletize more efficiently. Tighter stacking with less air space increases density. Pallet height matters - going from 36 inches to 48 inches with the same weight dramatically improves density.
• Consolidate smaller shipments. Shipping three separate half-pallets at Class 125 each costs more than one consolidated pallet at Class 85-100. If timing allows, hold freight for consolidation.
• Reduce oversized packaging. The same product in smaller packaging takes up less cubic space, improving density and potentially moving to a lower class.
• Consider a freight broker. Brokers have negotiated class-specific rates with multiple carriers and can often route your freight to the carrier with the best tariff for your specific class and lane.

LTL Accessorial Charges That Add to Your Bill

Freight class determines your base rate, but accessorial charges can add significantly to the final invoice. Common accessorials to know:

• Liftgate delivery ($75-150): Required when the destination has no loading dock. Residential deliveries almost always require liftgate.
• Inside delivery ($50-200+): When the carrier needs to move freight beyond the immediate delivery point (e.g., into a building, up stairs).
• Residential delivery ($50-150): Most LTL carriers charge a flat fee for residential stops.
• Limited access ($75-200): Applies to schools, churches, military bases, construction sites, and other locations with restricted access.
• Redelivery ($75-150): If no one is available to receive the shipment, a second delivery attempt triggers this charge.

Declare all relevant delivery conditions when booking. Surprise accessorials after delivery are harder to dispute than conditions disclosed upfront.

Use our Freight Class Calculator to calculate density and determine the right NMFC class for your shipment - before you book, not after delivery.