Freight class is a standardized rating from 50 to 500 that carriers use to price less-than-truckload (LTL) shipments, based mainly on density along with handling, stowability, and liability. The National Motor Freight Traffic Association (NMFTA) maintains this system, called the National Motor Freight Classification (NMFC), so that every shipper and carrier is pricing freight against the same standard.
Getting freight class right matters because it directly sets your LTL rate, and getting it wrong is one of the most common causes of unexpected reclassification charges on a freight invoice. This guide walks through what freight class is, how it is calculated, how it affects your shipping cost, and how ENorth Logistics’ Freight/Carrier Operations team helps clients avoid the classification errors that lead to billing surprises.
What Is Freight Class?
Freight class is a numerical rating, ranging from class 50 to class 500 across 18 distinct classes, that LTL carriers use to determine how much space, weight, and handling risk a shipment represents. A lower class, like 50, applies to dense, easy-to-handle freight and costs less to ship. A higher class, like 400 or 500, applies to lightweight, bulky, or fragile freight and costs more.
Every LTL shipment needs a freight class because carriers use it, combined with weight and distance, to calculate the shipping rate. Without an accurate class, a carrier cannot price a shipment correctly, and pricing based on the wrong class is one of the leading causes of billing disputes after delivery.
What Is NMFC and How Does the Classification System Work?
The National Motor Freight Classification (NMFC) is the standardized commodity classification system published by the NMFTA that assigns a freight class to virtually every type of product shipped by truck in the United States and, in practice, across much of North America’s LTL network. Each distinct commodity is assigned an NMFC number, sometimes called an NMFC item number, that describes the product’s material, packaging, and handling characteristics, and that number maps to a corresponding freight class.
The NMFC number and the freight class are related but not identical. The NMFC number identifies the specific commodity description, while the freight class is the pricing tier that description maps to. Two different NMFC numbers can point to the same freight class, and some commodities have a single NMFC number that spans a density-based range of classes, meaning the actual class depends on how dense that specific shipment is.
NMFC classifications are reviewed and updated periodically by the NMFTA, and a product’s classification can change over time as packaging, handling data, or industry practices evolve. Shippers who have not verified their NMFC number recently should confirm it is still current, since shipping under an outdated classification is a common cause of reclassification.
The 18 Freight Classes Explained
The NMFC system groups all commodities into 18 classes, and knowing where your product falls tells you roughly how it will be priced relative to other freight.
| Freight Class | Typical Density (lbs/cubic ft) | General Category |
|---|---|---|
| 50 | 50+ | Dense, durable freight (e.g., bricks, steel) |
| 55 | 35 to 50 | Bottled beverages, some appliances |
| 60 | 30 to 35 | Car parts, machinery |
| 65 | 22.5 to 30 | Auto parts, boxed books |
| 70 | 15 to 22.5 | Food items, car accessories |
| 77.5 | 13.5 to 15 | Tires, bathroom fixtures |
| 85 | 12 to 13.5 | Crated machinery |
| 92.5 | 10.5 to 12 | Computers, monitors |
| 100 | 9 to 10.5 | Boxed books, canvas |
| 110 | 8 to 9 | Cabinets, framed art |
| 125 | 7 to 8 | Small household appliances |
| 150 | 6 to 7 | Auto sheet metal parts |
| 175 | 5 to 6 | Clothing, stuffed furniture |
| 200 | 4 to 5 | Sheet metal parts, aircraft parts |
| 250 | 3 to 4 | Bamboo furniture, mattresses |
| 300 | 2 to 3 | Wood cabinets, tables |
| 400 | 1 to 2 | Deer antlers, fixtures |
| 500 | Less than 1 | Bulky, low-density, high-value goods |
Class 50 is the lowest and least expensive class because it represents dense freight that uses trailer space efficiently and carries low damage risk. Class 500 is the highest and most expensive because it represents freight that takes up significant trailer space relative to its weight, often combined with a higher risk of damage. As a general rule, the higher the freight class number, the more it costs to ship the same weight over the same distance.
The Four Factors That Determine Freight Class
Freight class is determined by four factors defined by the NMFTA: density, stowability, handling, and liability, with density serving as the primary driver under current classification guidelines. Understanding each factor helps explain why two products of similar size can carry very different freight classes.
- Density measures the weight of a shipment relative to its volume, expressed in pounds per cubic foot. This is the single most influential factor in most modern freight classifications.
- Stowability reflects how easily a shipment fits alongside other freight in a trailer. Oddly shaped items, hazardous materials, or freight that cannot be stacked reduce stowability and can raise the assigned class.
- Handling reflects how much extra care or equipment a shipment requires to load and unload. Freight that is fragile, oversized, or requires special equipment typically carries a higher class.
- Liability reflects the risk of damage, theft, or spoilage during transit. High-value, perishable, or easily damaged freight generally carries a higher class due to increased carrier liability exposure.
For most general commercial freight, density does the heaviest lifting in determining the final class, which is why calculating density accurately is the most important step for any shipper trying to estimate their freight class.
How to Calculate Freight Density
Freight density is the total weight of a shipment divided by its total volume in cubic feet, and it is the starting point for estimating freight class for most commodities. The calculation follows four steps:
- Measure the length, width, and height of the packaged shipment in inches, including the pallet if the freight is palletized.
- Multiply length by width by height to get the total cubic inches.
- Divide the total cubic inches by 1,728 to convert to cubic feet.
- Divide the total weight in pounds by the cubic feet to get the density in pounds per cubic foot.
Once you have the density in pounds per cubic foot, you can compare it against the density ranges in the freight class table above to estimate the likely class. Note that dimensions should reflect the full packaged shipment, pallet included, since carriers measure and bill based on the space the shipment actually occupies in the trailer, not just the product itself.
Worked Example: Calculating Freight Class for a Single Pallet
Consider a shipment on a standard 48-inch by 40-inch pallet, stacked 48 inches high, with a total weight of 800 pounds including the pallet.
- Cubic inches: 48 x 40 x 48 = 92,160 cubic inches
- Cubic feet: 92,160 divided by 1,728 = 53.3 cubic feet
- Density: 800 pounds divided by 53.3 cubic feet = 15.0 pounds per cubic foot
Based on the class table above, a density of 15.0 pounds per cubic foot falls near the boundary between class 65 and class 70. At this point, a shipper should confirm the exact NMFC number for the specific commodity being shipped, since the written commodity description, not density alone, ultimately governs the final classification in borderline cases.
How ENorth Logistics’ Team Handles This ENorth Logistics’ Freight/Carrier Operations team verifies freight class and NMFC number at intake, using the shipment’s actual dimensions and weight rather than the figures a client estimated when booking. This step is designed to catch density miscalculations and outdated NMFC numbers before a shipment moves, which helps prevent the reclassification charges that show up on a freight invoice weeks after delivery.
How Freight Class Affects LTL Shipping Costs
Freight class is one of the primary inputs LTL carriers use to calculate a shipping rate, alongside weight, origin and destination, and any accessorial services requested. A higher freight class generally means a higher rate for the same weight and distance, because it signals more trailer space used, more handling risk, or more liability exposure per pound shipped.
Other cost factors that combine with freight class to set the final LTL rate include:
- Weight and dimensional weight, since carriers price based on whichever is greater between actual weight and the space the shipment occupies
- Origin and destination lane, since rates vary by route and regional carrier capacity
- Fuel surcharges, which are typically calculated as a percentage of the base rate
- Accessorial charges, such as liftgate service, residential delivery, inside delivery, or limited-access locations, which are added on top of the base freight charge
Because freight class has this much influence on the final bill, shippers who consistently ship at the correct class, rather than guessing or defaulting to a familiar class from a past shipment, generally see more predictable LTL costs over time.
Finding the Correct NMFC Number for Your Product
Finding the correct NMFC number starts with identifying the specific commodity description that matches what you are actually shipping, since the NMFC catalog groups products by material, use, and handling characteristics rather than by generic product category. The NMFTA maintains the official NMFC database, and many carriers and freight brokers also provide lookup tools that reference the same underlying data.
To find or confirm an NMFC number:
- Identify the commodity’s material composition and intended use, since the same physical item can have different NMFC numbers depending on these factors.
- Check whether the commodity’s NMFC entry lists a single class or a density-based range of classes.
- If a range applies, calculate the shipment’s actual density using the method above to determine where it falls in that range.
- Confirm the NMFC number is current, since classifications are periodically reviewed and can change.
Shippers who ship the same product repeatedly should still periodically re-verify their NMFC number, since a classification that was correct a year ago is not guaranteed to still be current.
What Should Appear on the Bill of Lading
The freight class and NMFC number should both appear on the bill of lading (BOL), since this is the document carriers use to verify pricing and handling at pickup and during transit. An incomplete or inaccurate BOL is one of the most common triggers for a carrier reclassification.
A complete BOL for classification purposes should include:
- The correct NMFC number and freight class
- Accurate weight, including packaging and pallet
- Accurate dimensions of the packaged shipment
- A clear commodity description matching the NMFC entry
Responsibility for accurate classification on the BOL generally sits with the shipper, even though the carrier is the one who ultimately verifies and, if necessary, corrects it. This is why an incorrect class or weight on the BOL almost always results in a reclassification charge billed back to the shipper rather than the carrier absorbing the difference.
Freight Reclassification and How to Avoid It
Freight reclassification happens when a carrier inspects, measures, or weighs a shipment and determines that the class or weight declared on the BOL does not match the actual freight, resulting in a corrected, and usually higher, invoice. This is one of the most frequent sources of unexpected LTL charges.
Common causes of reclassification include:
- Incorrect dimensions or weight recorded on the BOL
- An outdated or incorrect NMFC number
- Packaging changes that were not reflected in the original classification
- A carrier’s dock inspection revealing the freight is denser, larger, or higher-risk than declared
To reduce the risk of reclassification, shippers should measure and weigh freight accurately at the point of shipment, including the pallet, and confirm the NMFC number matches the current classification for that commodity. If a reclassification charge does appear on an invoice, shippers can dispute it, but a successful dispute generally requires documentation, such as the original measurements, weight records, and NMFC verification, to counter the carrier’s revised figures.
How ENorth Logistics’ Team Handles This When a carrier flags a shipment for reclassification, ENorth Logistics’ Freight/Carrier Operations team reviews the original booking data against the carrier’s revised figures before the charge is passed on, and works directly with the carrier to resolve discrepancies using documented weight and dimension records. This is designed to catch billing errors and legitimate reclassifications early, rather than leaving clients to dispute an unexpected charge on their own after the fact.
Common Freight Classification Mistakes to Avoid
Most freight classification errors come from a small set of recurring mistakes, and avoiding them prevents the majority of reclassification issues shippers encounter.
- Estimating dimensions instead of measuring them. Rough estimates rarely match the density a carrier calculates at the dock.
- Forgetting to include the pallet in weight and dimensions. Carriers bill based on the full packaged shipment, not the product alone.
- Reusing an old NMFC number without checking for updates. Classifications change periodically, and an outdated number can trigger a reclassification.
- Assuming density alone sets the class. Handling, stowability, and liability can still push a shipment to a different class than density alone would suggest, particularly for fragile, hazardous, or oddly shaped freight.
- Not accounting for mixed pallets. When multiple commodities with different classes ship on one pallet, the carrier typically applies the highest applicable class to the entire pallet unless it is broken out separately.
How to Reduce LTL Shipping Costs Without Misclassifying Freight
Reducing LTL shipping costs comes down to shipping as dense and well-packaged as reasonably possible, not underclassifying freight to get a lower rate, since underclassification simply results in a reclassification charge later. Legitimate cost-reduction strategies include:
- Consolidating shipments to improve density where possible
- Using packaging that protects the product without adding unnecessary bulk or weight
- Confirming the correct NMFC number rather than defaulting to a familiar but potentially outdated class
- Comparing quotes across carriers for the same accurate classification, rather than shopping quotes based on different declared classes
How ENorth Logistics’ Team Handles This ENorth Logistics’ Freight/Carrier Operations team works with clients during LTL booking to confirm classification accuracy up front, matching each shipment to the right carrier within its established network based on lane, weight, and class. Because shipment and classification data run through the same platform clients use for tracking and inventory visibility, class-related issues are usually caught before a shipment moves rather than discovered on the invoice afterward.
Frequently Asked Questions
What is freight class in simple terms?
Freight class is a standardized rating from 50 to 500 that tells an LTL carrier how much space, weight, and handling risk a shipment represents, which the carrier then uses to calculate the shipping rate.
What is the difference between freight class and an NMFC number?
The NMFC number identifies the specific commodity description, including its material and use, while freight class is the pricing tier that description maps to. Some NMFC numbers correspond to a single class, while others map to a density-based range of classes.
How do I calculate my freight class?
Measure the length, width, and height of the packaged shipment in inches, including the pallet, multiply those dimensions together and divide by 1,728 to get cubic feet, then divide the total weight by the cubic feet to get density in pounds per cubic foot. Compare that density against the NMFC class ranges for your specific commodity to estimate the class.
Does pallet weight count toward freight density?
Yes. Freight density calculations should include the full packaged shipment, pallet included, since carriers bill based on the total space and weight the shipment occupies in the trailer.
Why did my freight get reclassified after pickup?
Reclassification usually happens when a carrier’s dock inspection finds that the actual weight, dimensions, or commodity does not match what was declared on the bill of lading, often due to estimated rather than measured dimensions or an outdated NMFC number.
Can I dispute a freight reclassification charge?
Yes, but a successful dispute generally requires documentation such as the original measurements, weight records, and confirmation of the correct NMFC number to counter the carrier’s revised figures.
Does a higher freight class always cost more to ship?
Generally, yes, for the same weight and distance. Higher classes reflect lower density, more handling difficulty, or higher liability risk, all of which carriers price at a premium compared to dense, easy-to-handle, low-risk freight.
What information do I need before requesting an LTL freight quote?
You need accurate weight and dimensions of the full packaged shipment, the correct freight class and NMFC number, the origin and destination, and any accessorial services required, such as liftgate or residential delivery.
