Less-Than-Truckload (LTL) shipping uses a standardized system called freight class to determine the cost of transporting goods. This classification system ensures pricing accurately reflects the difficulty and risk involved in moving different types of cargo. Officially governed by the National Motor Freight Classification (NMFC), understanding how to determine the correct class is essential for any business shipping LTL freight. Misclassifying goods can lead to significant billing errors and delays.
Understanding the Purpose of Freight Class
Freight class is used to establish a common structure for pricing LTL shipments across the carrier industry. This standardization ensures carriers can quickly assess the transportability of a commodity. The National Motor Freight Traffic Association (NMFTA) develops and maintains the official National Motor Freight Classification (NMFC) tariff, which is the authoritative source for all classification rules.
The NMFC system assigns a class number to every shippable item based on its characteristics, ranging from 50 (easiest and least expensive to transport) to 500 (most difficult or high-risk commodities). Freight with a lower class number generally occupies less space and poses less risk, resulting in lower shipping rates. Conversely, a higher class signifies specialized handling or disproportionate space usage, leading to higher transportation costs.
The Four Primary Characteristics That Determine Class
Density
The NMFC relies on four distinct physical characteristics of a shipment to assign the appropriate class number. The most frequently referenced factor is density, which measures the weight of the freight in relation to the space it occupies. This metric helps carriers gauge how efficiently the commodity will fill a trailer.
Other Factors
The three other considerations are stowability, handling, and liability. Stowability assesses how easily the freight can be transported alongside other items and whether it can be safely stacked. Handling focuses on the ease of moving the item and whether it requires specialized equipment or procedures due to its shape or fragility. Liability measures the risk associated with the freight, encompassing its monetary value and the potential for theft or damage during transit.
Step-by-Step Guide to Calculating Shipping Density
Determining accurate density is the foundational mathematical step in classifying most LTL freight. Shippers must first measure the length, width, and height of the entire shipment in inches, ensuring all dimensions include the pallet, packaging, and any overhang. To find the cubic feet measurement, multiply the length, width, and height, then divide the total by 1,728, which is the number of cubic inches in a single cubic foot.
The calculation also requires the shipment’s total weight in pounds, including the pallet and packaging materials. Density in pounds per cubic foot (PCF) is found by dividing the total weight by the total cubic feet.
Example Density Calculation
For example, a shipment weighing 500 pounds and measuring 48 x 40 x 60 inches: First, 48 x 40 x 60 equals 115,200 cubic inches. Dividing 115,200 by 1,728 yields a total volume of 66.67 cubic feet. Finally, dividing the 500 pounds of total weight by 66.67 cubic feet results in a calculated density of 7.5 PCF. Precision in these measurements is important, as slight rounding errors can result in a different freight class and shipping rate.
Mapping Density to the Official Freight Class Number
After calculating the density, the resulting pounds per cubic foot (PCF) value is used to map the shipment to a preliminary freight class number. A higher density corresponds to a lower class number because the freight is more space-efficient and less costly to transport. This inverse relationship means that as the PCF increases, the freight class decreases.
The density-to-class mapping follows a regulated schedule, and shippers should consult the official NMFC tariff for precise ranges. For example, a low density commodity (1 PCF) typically falls into the highest class (Class 500), while a highly dense shipment (50 PCF or more) usually qualifies for the lowest class (Class 50). The 7.5 PCF example would likely be assigned a class near Class 85 or Class 92.5. While density is the primary determinant for many commodities, the final classification is officially determined by the specific NMFC item number associated with the commodity itself, which may override the density calculation.
How Handling, Stowability, and Liability Influence Classification
While density provides a mathematical basis, the three remaining transportability factors often increase the freight class regardless of the commodity’s density.
Handling
Handling considerations apply when a shipment requires specialized mechanical equipment or manual effort outside of standard pallet jack or forklift procedures. For example, extremely long pipes or oddly shaped machinery that cannot be easily moved may be assigned a higher class because they complicate the carrier’s loading and unloading processes.
Stowability
Stowability refers to the ability of the freight to be safely loaded with other commodities and stacked within the trailer space. Items that are inherently hazardous, such as flammable liquids, or freight marked “Do Not Stack” due to fragility or instability, compromise the efficient use of trailer space. These restrictions mandate a higher freight class because the carrier cannot maximize the trailer’s capacity.
Liability
Liability factors relate to the financial risk the carrier assumes when transporting the goods. High-value commodities like electronics or precious metals carry an increased risk of theft or catastrophic loss, necessitating a higher classification. Extremely fragile items that have a high probability of damage during transit will also be placed in a higher class to offset the carrier’s increased exposure to financial risk.
Avoiding Costly Errors and Reclassification Fees
Operational errors in the measurement and classification process are a common source of unexpected shipping costs and significant reclassification fees. A frequent mistake is rounding dimensions or weight down slightly, which triggers an audit by the carrier. Failing to include the full weight and dimensions of the pallet and all packaging materials also consistently leads to misclassification.
When a carrier determines the provided information was incorrect, they perform a reweigh and re-measure audit, resulting in a re-bill for the shipper. This re-bill uses the higher, corrected freight class and is often accompanied by administrative fees for the audit itself. These surprise charges can increase the final invoice, sometimes doubling the original quoted price.
To mitigate these financial risks, shippers should use certified, regularly calibrated scales and precise measuring devices. Adopting a policy of measuring to the highest point and widest edge, including any bowing or bulging of packaging, helps ensure accuracy. Verifying the commodity’s NMFC item number against the official tariff before the shipment moves provides the strongest defense against costly reclassification.