Resources / Freight Class Guide
Freight class is where LTL invoices go right or wrong. Here's how the system works, how to calculate your density, and how to keep reweighs and reclassifications off your bills — from the specialists who audit every one.
Measure each handling unit at its longest, widest, and tallest points — pallet and overhang included — and use the actual scale weight.
Under the NMFC's standardized density scale (expanded to 13 tiers in the 2025 overhaul), density-rated freight classes as follows:
| Density (lbs/cu ft) | Class |
|---|---|
| Less than 1 | 400 |
| 1 but less than 2 | 300 |
| 2 but less than 4 | 250 |
| 4 but less than 6 | 175 |
| 6 but less than 8 | 125 |
| 8 but less than 10 | 100 |
| 10 but less than 12 | 92.5 |
| 12 but less than 15 | 85 |
| 15 but less than 22.5 | 70 |
| 22.5 but less than 30 | 65 |
| 30 but less than 35 | 60 |
| 35 but less than 50 | 55 |
| 50 or greater | 50 |
Freight class is a rating from 50 to 500 assigned to LTL freight under the National Motor Freight Classification (NMFC), maintained by the NMFTA. It exists so that carriers hauling thousands of different commodities in the same trailer can price them consistently. The lower the class, the less you generally pay per pound: class 50 is dense, durable freight that stacks; class 500 is light, bulky, or fragile freight that eats trailer space.
Class is determined by four characteristics:
Since the NMFTA's 2025 overhaul, most general commodities are classed on the 13-tier density scale alone — which means your dimensions and weights, not a lookup table, decide what you pay. Freight with special stowability, handling, or liability characteristics still carries its own NMFC rules.
Every major LTL carrier runs certified scales and laser dimensioners at their terminals. If the class on your bill of lading doesn't match what their equipment measures, they don't call to discuss it — they issue a reweigh or reclassification, adjust the invoice upward, and often add an inspection fee. On a class-sensitive lane, a bump from class 70 to 92.5 can add hundreds of dollars to a single shipment.
This is the single most common source of surprise LTL charges — and it's preventable.
At Logistics Fox, class review is built into the workflow: our team and the FoxIQ suite check class and density before your freight ships, and FoxIQ Audit compares 100% of carrier invoices against the quote afterward. When a carrier reclassifies, we catch it, pull the documentation, and file the dispute — before the bill reaches you. It's why our customers' invoices come back right.