Freight class is a standardized code that groups shipped commodities into 18 classes from 50 to 500, and it is a main driver of less-than-truckload (LTL) shipping rates. Lower classes are dense freight that ships cheaply; higher classes are light or bulky freight that costs more.
Freight class is the single number on a bill of lading that quietly sets much of what you pay to ship an LTL pallet. Get it right and your rate is accurate and stable; get it wrong and the carrier reweighs, reclassifies, and bills you the difference plus a fee weeks later. This post explains what freight class is, how density and three other factors set it, how to calculate density and classify a shipment, and how to avoid reclassification charges. It is educational and names no products.
What is freight class?
Freight class is a standardized grouping, defined by the National Motor Freight Classification (NMFC) system, that sorts every commodity into one of 18 classes so LTL carriers can price shipments consistently. The 18 classes are 50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400, and 500. A lower class number means freight that is dense, stackable, sturdy, and cheap to move; a higher class means freight that is light for its size, hard to handle, or easily damaged, and therefore more expensive per pound.
The system exists so that a carrier moving thousands of different products can price them by a common yardstick instead of negotiating every commodity from scratch. It applies to LTL freight, where many shippers share a trailer, and it is far less relevant to full-truckload moves where you pay for the whole trailer regardless of what fills it. For a plant shipping finished goods out by the pallet, class is one of the levers that decides the freight bill.
How is freight class determined?
Freight class is determined by four characteristics of the commodity: density, stowability, handling, and liability, with density usually carrying the most weight. Density is how many pounds the freight packs into each cubic foot; stowability is how easily it fits alongside other freight; handling is how much special care it takes to load and move; and liability is the risk of theft, damage, or damage to nearby freight. The denser, more stackable, sturdier, and lower-risk the freight, the lower the class and the lower the rate.
Recent updates to the classification standard have pushed it further toward density. A restructuring that took effect in 2025 reorganized many commodity listings around a set of density tiers, so for a large share of freight the class now follows more directly from pounds per cubic foot. The other three factors still adjust the class for commodities that are unusually fragile, hard to stow, or high-risk, but density is the number to know first.
How do you calculate freight density?
You calculate density by dividing the shipment's total weight by its total volume in cubic feet, including the pallet and packaging. Measure the length, width, and height of the palletized shipment in inches, multiply them for cubic inches, divide by 1,728 to get cubic feet, then divide the weight by that figure. The result, in pounds per cubic foot, is the number that most often points to the class.
Take a standard pallet measured at 48 by 40 by 48 inches. That is 92,160 cubic inches, which divided by 1,728 is 53.3 cubic feet. If the loaded pallet weighs 400 pounds, its density is 400 divided by 53.3, or about 7.5 pounds per cubic foot, a light, bulky load that lands in a high class. Load that same pallet to 1,200 pounds and the density jumps to about 22.5 pounds per cubic foot, a much denser load that drops to a lower class and a lower rate per pound. Same footprint, three times the weight, and a materially cheaper class, which is the whole logic of density-based pricing.
The table below shows the general direction density pushes the class. Read it as a guide, not a lookup: the actual class for many commodities still comes from the specific NMFC listing, which can pin a class regardless of density or adjust for handling and liability.
| Approx. density (lb/ft³) | Direction of class | Typical rate effect |
|---|---|---|
| 30 and above | Low class (around 50–70) | Lowest cost per pound |
| 15 to 30 | Mid-low class (around 70–92.5) | Below-average cost |
| 8 to 15 | Middle class (around 100–125) | Average cost |
| 4 to 8 | High class (around 150–250) | Above-average cost |
| Under 4 | Highest class (around 300–500) | Highest cost per pound |
How do you classify a shipment correctly?
Classify a shipment by measuring and weighing it accurately, calculating density, then confirming the class against the NMFC listing for that exact commodity. Guessing the class, or copying last year's number, is how reclassification charges start. The steps below keep it clean.
- Measure the packaged shipment. Record length, width, and height of the palletized load in inches, including the pallet and any overhang.
- Weigh the whole load. Get the actual gross weight, pallet and packaging included, not an estimate from the packing list.
- Calculate density. Convert the dimensions to cubic feet and divide the weight by that volume to get pounds per cubic foot.
- Find the NMFC item. Look up the specific commodity in the classification, because many items have an assigned class or a density scale that overrides a rough guess.
- Confirm the class and any sub-number. Match your density and commodity to the correct class and NMFC item number, noting any packaging conditions the listing requires.
- Put it on the bill of lading. Record the class, weight, dimensions, and NMFC number accurately so the carrier prices from your numbers, not their inspection.
Doing this consistently is a small discipline that protects margin on every LTL move, and it fits the same waste-cutting mindset as lean manufacturing and a leaner outbound flow. Sloppy classification is a quiet form of transportation waste: money lost not to the miles but to the paperwork.
Why does the wrong freight class cost you?
The wrong class costs you because carriers verify what you ship, and when their inspection disagrees with your bill of lading, they reclassify the freight and rebill you, often with an added correction fee. Many carriers run dimensioner and scale systems that automatically capture the real weight and cubic dimensions of every pallet. If you declared a lower, cheaper class than the freight actually warrants, the correction lands weeks later as an adjusted invoice for the higher class plus the reclassification charge, which turns a rate you thought you locked into an unpredictable one.
It cuts both ways. Declare too high a class and you simply overpay, quietly, on every shipment, with no refund coming because you volunteered the higher rate. Declare too low and you invite the reclass bill and the fee. Accurate classification is the only position that is stable, and it is worth the few minutes it takes, especially on freight you ship repeatedly, where a single wrong class multiplies across every load for a year.
What do the standards say?
Context from the governing body and primary references:
- The National Motor Freight Classification and its 18 classes are maintained by the National Motor Freight Traffic Association (NMFTA) which publishes the commodity listings and the density-based classification standard carriers price from.
- The NMFTA restructuring that took effect in 2025 reorganized many commodity listings around density tiers, making density the primary driver of class for a large share of LTL freight, per the association's classification updates.
- The freight this governs moves a large economy: the Bureau of Transportation Statistics and the Bureau of Labor Statistics track the trucking and manufacturing sectors that ship it, including roughly 13 million manufacturing jobs whose output moves largely by road.
The consistent point: freight class is a real, governed standard, not a carrier's opinion, and density is increasingly the number that sets it.
Where freight classification goes wrong
Freight classification goes wrong when the numbers on the bill of lading are not the numbers on the dock. The class is only as good as the weight and dimensions behind it, and in many plants those come from a stale product spec, a rounded estimate, or last quarter's paperwork rather than the actual pallet leaving today. When the carrier's dimensioner says otherwise, the reclass bills follow, and no one connects them back to the sloppy data that caused them.
Harmony is an AI-native layer that connects machines, software, and paperwork into one operational record, with no rip-and-replace, so shipment weights, dimensions, and the commodity details that drive class stop living in disconnected spreadsheets and become one current record. AI search returns cited answers across those records, so a shipping lead can ask what class and NMFC number a given product shipped under last time, or why a carrier reclassified a load, and get a real answer instead of digging through old bills of lading. It is the same paper-to-digital move Harmony makes elsewhere on the floor (see the CLS case study), and it supports the broader discipline of a lean supply chain and tighter inbound and outbound logistics. Harmony's digital workflows keep the shipping data accurate so the class on the bill of lading matches the freight on the truck.