What is LTL freight class and why does it matter?

LTL freight class is a standardized rating system defined by the NMFC (National Motor Freight Classification) that determines your shipping rate. Classes range from 50 to 500 - lower classes cost less to ship. The same 500 lb shipment can cost 8-10x more depending on whether it is Class 50 or Class 500. Getting the class wrong means surprise reclassification invoices after delivery.

How is freight class calculated?

Most freight class is determined by density - weight in pounds per cubic foot. Calculate cubic feet by multiplying length by width by height in inches and dividing by 1,728. Then divide the total weight by cubic feet to get density. Higher density means a lower (cheaper) freight class. Some commodities also have specific NMFC item numbers that override the density-based classification.

What freight class should I use for my shipment?

Calculate your shipment's density in pounds per cubic foot and match it to the class table. For example, a density of 15-22.5 lbs per cubic foot is Class 70. Densities below 1 lb per cubic foot are Class 500, the most expensive. When in doubt, classify slightly higher - it is better to slightly overpay upfront than receive a reclassification invoice for underclassifying.

What happens if I use the wrong freight class?

The carrier will re-weigh and re-measure your shipment at delivery and issue a classification correction invoice, often weeks after delivery. A shipment billed at Class 70 that gets reclassified to Class 100 can result in a 30-50% higher invoice. These corrections are very common and are one of the most frequent sources of freight billing disputes.

What is the difference between LTL and FTL shipping?

LTL (less-than-truckload) means your freight shares trailer space with other shippers' cargo. You only pay for the space your shipment occupies. FTL (full truckload) means you rent the entire trailer. LTL is cost-effective for shipments from one pallet to about 10-12 pallets. Above that, FTL usually becomes cheaper. Freight class applies only to LTL - FTL pricing is based on mileage and weight, not NMFC class.

Freight6 min readFebruary 15, 2026

LTL Freight Class Guide: How NMFC Classes Work

NMFC freight classes determine your LTL shipping rate. Learn how density determines class, the most common freight classes, what misclassification costs you, and how to classify your shipment correctly.

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.

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

Try the free tool

Freight Class Calculator →

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