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Understanding LTL Freight Class: A Complete Guide for Shippers

Freight class determines your LTL shipping rates. Learn how it's calculated, why it matters, and how to minimize costs.

· 3 min read

What is LTL freight class?

LTL (less-than-truckload) freight class is a standardized number from 50 to 500 that carriers use to price shipments that do not fill an entire trailer. The classification system is published by the National Motor Freight Traffic Association (NMFTA) in the National Motor Freight Classification (NMFC) directory.

Lower classes (50, 55, 60) are cheap to ship: dense, durable, easy to stack. Higher classes (300, 400, 500) are expensive: light, fragile, awkward, or high-value.

The four characteristics that determine class

Every NMFC classification considers four transportation characteristics:

  1. Density - pounds per cubic foot. The single biggest driver for most commodities.
  2. Stowability - can it stack? Any unusual dimensions or hazardous properties?
  3. Handling - special equipment, careful loading, or extra labor required?
  4. Liability - risk of theft, damage, perishability, or damage to adjacent freight.

For density-based NMFC items, you can calculate class directly from pounds per cubic foot. For most other items, the NMFC assigns a fixed class regardless of density.

How to calculate density

Density (lb/ft^3) = Total weight (lb) / Total volume (ft^3)
Volume (ft^3) = (L x W x H in inches) / 1728

Include pallets, crating, and any packaging in both weight and dimensions. Carriers measure the outside of the shipment, not just the product.

Density-to-class table (typical)

Density (lb/ft^3) Class
50+ 50
35 - 50 55
30 - 35 60
22.5 - 30 65
15 - 22.5 70
13.5 - 15 77.5
12 - 13.5 85
10.5 - 12 92.5
9 - 10.5 100
8 - 9 110
7 - 8 125
6 - 7 150
5 - 6 175
4 - 5 200
3 - 4 250
2 - 3 300
1 - 2 400
under 1 500

Why misclassification is expensive

If you ship at class 70 and the carrier reweighs and reclasses to class 125, you will receive a reclassification charge plus the rate difference, often weeks after delivery. Repeated misclassifications also damage your relationship with the carrier.

Practical checklist before you book

  • Weigh the palletized shipment, not just the product.
  • Measure to the longest, widest, tallest point including overhang.
  • Look up the NMFC item number for your commodity if one exists.
  • Use a density calculator for density-based items.
  • Document everything on the BOL: piece count, weight, dimensions, NMFC number, and class.

Try it yourself

Use our Freight Class Calculator to enter dimensions and weight and get the suggested density-based class instantly.

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