If you declare the wrong freight class on a bill of lading, a carrier's terminal scale or dimensioner will catch it and reclassify the load. Then they’ll send you an invoice for the difference, plus a re-class fee and other accessorial charges, that shows up weeks after the truck left your dock. And thanks to the biggest freight classification overhaul in decades, your risk of misclassifying freight is on the rise.
This guide explains what freight class is, the four classification factors considered, how to calculate density correctly under the new rules, and how using the right TMS helps protect you from making costly reclassification errors.
What Is Freight Class?
Freight class is the pricing tier that every less-than-truckload (LTL) shipment is assigned before a carrier will quote it. The National Motor Freight Classification (NMFC) — maintained by the NMFTA — sorts freight into 18 classes, running from Class 50 (the densest, cheapest-to-ship freight) to Class 500 (the least dense, most expensive-per-pound freight). Every NMFC item number maps to a class, and carriers' rating engines use class to set your base rate.
A pallet of steel and a pallet of styrofoam can weigh the same and cost wildly different amounts to move because one takes up far more trailer space per pound. Freight class is the industry standard for quantifying that trade-off across carriers, brokers, and shippers. And if your team or software is still classifying freight the way it did in 2024, you're likely quoting against item numbers that no longer exist.
Four Factors That Determine Freight Class in 2026
Here are the specific things carriers consider when assigning freight class:
Density: How much weight is packed into the shipment’s volume? Measured in pounds per cubic foot (PCF). After the 2025 reform, density became the primary driver of class for most commodities.
Stowability: How easily will the shipment load alongside other freight in a trailer? Odd shapes, hazardous materials, or freight that can't be stacked or stored near other goods pushes a class higher, regardless of density.
Handling: Does the shipment require special equipment, extra care, or additional labor for loading and unloading? Fragile or oversized freight carries a handling penalty even if it's dense.
Liability: Is there a significant risk of theft, damage, or spoilage? High-value electronics and perishable goods often carry a higher class than their density alone would suggest, because carriers price in the risk of a claim.
Although density is the primary driver of class assignment, the other three factors can override it, meaning two shipments with identical PCF can land in different classes.
What Changed with the 2025–2026 NMFC Reform
Before July 2025, Classes 50 and 55 could only be assigned through a specific NMFC commodity code. Enacted by the National Motor Freight Traffic Association (NMFTA) on July 19, 2025, Docket 2025-1 shifted the freight classification system from commodity-based rules to density-based rules — and just six and a half months later, Docket 2026-1 introduced even more changes.
First, Docket 2025-1 expanded the density scale from 11 sub-provisions to 13, adding two new tiers at the top:
- Sub 11: 30–35 lbs/ft³ → Class 60
- Sub 12: 35–50 lbs/ft³ → Class 55
- Sub 13: 50+ lbs/ft³ → Class 50
For the first time, freight above 35 PCF can qualify for Class 55 or 50 solely on density, regardless of its contents.
As part of the rollout of Docket 2026-1, effective February 6, 2026, roughly 2,000 NMFC item numbers were consolidated or reclassified. Additional legacy items were canceled, and the reform tightened the rules on how carriers apply the new structure.
For industrial shippers moving metals, lumber, and other high-density bulk freight, this presents a new opportunity because dense freight now qualifies for Class 50 and 55 pricing that wasn't available under the old commodity-based rules — but only if your classification data is current.
Comprehensive NMFC Freight Class List (18 classes)
How to Calculate Freight Class
Follow these steps to calculate and identify the correct freight class.
Step 1: Measure Your Shipment: Measure length, width, and height in inches, including the pallet and any packaging. If freight overhangs the pallet, measure the freight's actual footprint, not just the pallet's.
Step 2: Calculate Cubic Feet: Multiply length × width × height, then divide by 1,728 (the number of cubic inches in a cubic foot). Example: a pallet measuring 48" × 40" × 48" = 92,160 cubic inches ÷ 1,728 = 53.3 cubic feet.
Step 3: Calculate Density (PCF): Divide total weight in pounds by cubic feet. Example: a pallet of steel brackets weighing 2,800 lbs at 53.3 cubic feet = 52.5 lbs/ft³.
Step 4: Match Density to Freight Class: At 52.5 PCF, that pallet of steel brackets qualifies for Class 50 — the lowest, cheapest class on the chart, and one that wasn't available on a density basis before the 2025 reform. Compare that to a pallet of the same dimensions holding lightweight packaging material at 400 lbs: 400 ÷ 53.3 = 7.5 PCF, which lands at Class 125. Same footprint, five classes apart.
Freight Class Density Calculator
How Freight Class Affects Your LTL Rate
Let’s look at two identical shipments moving the same lane, at the same weight, in the same-size box. The only difference is how tightly one is packed.
- Shipment A: 1,000 lbs, packed into a 48" × 40" × 48" pallet at full density
Density = 18.8 PCF → Class 70 - Shipment B: 1,000 lbs, packed loosely into a 48" × 40" × 72" pallet.
Density = 12.5 PCF → Class 85.
Even though shipment B is the same weight, it contains more air. But that single-class jump made on a typical 500-mile lane can add hundreds of dollars to the rate.
Multiply that across a fleet of shipments moving every week, and it’s easy to see why the hidden costs of freight misclassification (like loose packing or a miscalculated class) compound fast.
The Most Common Freight Class Mistakes
- Using outdated commodity-based NMFC codes: The single biggest risk since the 2025 reform. Teams still classifying by commodity description rather than current density thresholds are quoting against item numbers that may no longer exist — and finding out when the invoice comes back higher than expected.
- Forgetting to include pallet weight and dimensions: Underestimating the total shipment weight or footprint by omitting the pallet is one of the most common triggers for a carrier reclassification upon arrival.
- Misclassifying bulk and industrial commodities: Density varies significantly by form factor, even within the same commodity. A coil of steel and a bundle of steel pipe are not the same class — the coil's tight, uniform shape packs weight far more efficiently than the pipe's irregular stacking profile, even though both are "steel" on a packing slip.
- Not documenting the basis for your classification: Without a documented density calculation and NMFC code on file, disputing a carrier's reclassification is nearly impossible. Keep the math — dimensions, weight, and resulting PCF — on the bill of lading or in your TMS, not just in someone's head.
Details matter, and even a minor miscalculation can be majorly costly.
How Using a TMS Minimizes Reclassification Risk
Most errors are caused by mistakes made during manual classification. Maybe a dimension gets estimated instead of measured, a commodity gets coded from memory instead of the current NMFC table, or no one caught that a shipment's density crossed a class threshold since the last time it moved.
A TMS with a built-in freight audit solution catches discrepancies before they cost you money. The system cross-checks declared classes against actual shipment data and flags mismatches before the truck leaves the dock, not weeks later when the adjusted bill arrives.
For industrial shippers running high volumes of LTL alongside truckload, rail, and intermodal, the audit layer needs to work across all modes, not just one. The same goes for shippers that manage carriers and private fleets within a single network.
See how Princeton TMX's multimodal freight management approach keeps classification and audit consistent regardless of how a shipment moves. Accurate, current classification data also strengthens freight planning across your network.
Ready to stop paying for classification errors? Request a demo or learn more about how our freight audit solution catches reclassification errors before they impact your invoice.
Freight Class Frequently Asked Questions
Freight class is a standardized rating system, maintained by the NMFTA, that assigns every LTL shipment to one of 18 pricing tiers (Class 50 to Class 500) based on density, stowability, handling, and liability. Carriers use it to set the base rate for a shipment.
Measure length, width, and height in inches (including pallet and packaging), multiply to get cubic inches, divide by 1,728 to get cubic feet, then divide total weight in pounds by cubic feet. The result is density in pounds per cubic foot (PCF), which maps to a class on the NMFC density scale.
Density-based classes are determined purely by a shipment's weight-to-volume ratio. Item-based (commodity-based) classes are tied to a specific NMFC code regardless of density. Since the 2025–2026 reform, most commodities — including, for the first time, Classes 50 and 55 — are density-based, though some items still carry fixed commodity codes that override density.
Even a dense shipment can be bumped to a higher class if it requires special handling equipment, can't be stacked or stowed efficiently with other freight, or carries elevated liability risk (theft, damage, spoilage). Density sets a baseline; these factors can push the final class higher.
The carrier's terminal will typically catch the discrepancy through weighing and dimensioning equipment, reclassify the shipment to the correct class, and rebill you for the rate difference — often with an added reclassification fee.
Yes. NMFTA Docket 2025-1, effective July 19, 2025, shifted the system from commodity-based to density-based classification, expanded the density scale from 11 to 13 tiers, and made Classes 50 and 55 available on density alone for the first time. Docket 2026-1, effective February 6, 2026, retired additional legacy commodity codes.
Cross-reference your commodity against the current NMFC database (NMFTA's ClassIT+ platform is the official digital source) or confirm the code directly with your carrier or TMS provider, especially if your last classification predates the 2025 reform.
