LTL Freight Class Explained: How NMFC Classes Affect What You Pay

What freight class is and why it exists

Less-than-truckload carriers move thousands of different products on the same trailers every day. A pallet of steel bolts and a pallet of foam pillows can weigh very different amounts while taking up the same floor space, and they create very different costs and risks for the carrier. Freight class is the system the industry uses to account for those differences so that pricing is consistent from one shipper to the next.

In North America, freight class comes from the National Motor Freight Classification, usually shortened to NMFC. The NMFC is maintained by the National Motor Freight Traffic Association and assigns commodities to one of eighteen classes, ranging from class 50 at the low end to class 500 at the high end. Every LTL tariff and almost every LTL rate quote is built on top of that classification, so understanding it is one of the most useful things a shipper can do.

Full truckload and dedicated equipment are usually priced by the mile or by the trip rather than by class. Freight class matters most when your freight shares space on a trailer with other shippers and moves through a terminal network, which is exactly how LTL works.

The four factors that determine a class

The NMFC looks at four transportation characteristics when it assigns a class to a commodity. Knowing them helps you predict where your freight will land and spot mistakes before they cost you money.

• Density: how much the shipment weighs for the space it takes up, measured in pounds per cubic foot. This is the biggest factor for most freight.
• Stowability: whether the freight can be stacked, loaded alongside other freight, or must be kept apart because it is hazardous, oddly shaped, or excessively long.
• Handling: whether the freight needs special care, such as fragile goods, items that cannot be forklifted easily, or loads that need extra labor at the dock.
• Liability: how likely the freight is to be damaged, stolen, or to damage other freight, and how valuable it is relative to its weight.

How to calculate freight density

Because density drives so much of the class decision, every shipper should be comfortable calculating it. The math is simple, and doing it before you book is far cheaper than finding out from a carrier inspection later.

Start by measuring the length, width, and height of each handling unit in inches, including the pallet and any overhang. Multiply the three numbers together to get cubic inches, then divide by 1,728 to convert to cubic feet. Finally, divide the total weight of the unit, including the pallet and packaging, by the cubic feet. The result is pounds per cubic foot.

For example, a standard 48 by 40 inch pallet stacked 50 inches high is 96,000 cubic inches, or about 55.6 cubic feet. If that pallet weighs 600 pounds, its density is roughly 10.8 pounds per cubic foot. On a density-based scale, that would typically place it in a mid-range class. Stack the same product to 70 inches and the density drops, which can push it into a higher, more expensive class even though the weight barely changed.

Always measure at the widest and tallest points. Carriers use dimensioning equipment at their terminals, and if a pallet is taller than declared because of a protruding box or loose shrink wrap, the scanner will catch it.

Recent changes to the NMFC

Over the past few years, the NMFTA has moved a large number of commodities away from fixed, item-specific classes toward density-based classification. The goal is to make classes easier to determine and more consistent with how carriers actually measure freight today. For shippers, the practical result is that density matters even more than it used to, and some long-standing class assignments have changed.

If you have been using the same class on your bills of lading for years, it is worth reviewing those descriptions against the current classification. A product that used to ship as a single fixed class may now be rated on density, and carriers will invoice based on the current rules regardless of what an old routing guide says.

Why reclass and reweigh fees happen

A reclass happens when the carrier inspects a shipment and decides it belongs in a different class than the one on the bill of lading. A reweigh happens when the scale weight differs from the declared weight. Either one changes the price after the freight has already moved, and most carriers add an inspection fee on top of the corrected charges.

The most common causes are estimating dimensions instead of measuring them, forgetting to include pallet weight, using a generic commodity description such as "general merchandise," and copying a class from an old shipment without checking whether the product or packaging has changed. Mixed pallets with several different products are another frequent source of disputes, since each item may carry its own class.

You can dispute a reclass if you have documentation, such as photos of the measured pallet, a scale ticket, or a product specification sheet. Disputes are much easier to win when that evidence was collected before pickup rather than reconstructed afterward.

Practical ways to lower your LTL cost

Freight class is not just something that happens to you. Packaging and loading decisions directly change density, and density directly changes class. A few habits make a measurable difference over a year of shipping.

• Build pallets as dense and square as possible, and avoid stacking light product unnecessarily high.
• Use the smallest pallet footprint that safely holds the product, and avoid overhang.
• Make pallets stackable where the product allows it, because non-stackable freight is often charged for the space above it.
• Describe the commodity specifically and accurately on the bill of lading, including NMFC item numbers when you know them.
• Weigh and photograph every handling unit before pickup and keep the records with the shipment.
• Ask about volume LTL or partial truckload quotes once you reach six or more pallets, since these are often priced on space rather than class.

Freight class and accessorial charges

Even when the class is right, the final invoice can still differ from the quote because of accessorial charges. Liftgate service, residential delivery, inside delivery, limited-access locations such as schools and construction sites, and delivery appointments all add cost. These services are usually priced separately from the linehaul rate, so they need to be requested at booking.

The cleanest LTL invoices come from quotes that include accurate dimensions, accurate weight, the correct class, and every accessorial the shipment will actually need. Leaving one out to make a quote look cheaper almost always costs more once the carrier bills it later.

How LIME Logistics helps with LTL

LIME Logistics books LTL shipments across the United States and Canada through a vetted network of regional and national carriers. When you request a quote, we review the commodity, dimensions, and weight with you so the class and accessorials are right the first time. If a shipment is close to the line between LTL and truckload, we will price both options so you can see the tradeoff between cost, transit time, and handling.

Based in Buffalo, NY, we also handle cross-border LTL into Ontario and Quebec, where accurate paperwork matters as much as accurate dimensions. If you are not sure how to classify a product, send us the specifications and we will help you work it out before the freight ships.

Frequently asked questions