What are Freight Class Codes? Complete Guide

Freight shipping can be confusing, especially when it comes to pricing. One of the most important factors that determines your shipping costs in less-than-truckload (LTL) freight is the freight class code. If you’ve ever seen “NMFC” on a bill of lading and wondered what it means, this guide will walk you through it.

What is a Freight Class Code?

Freight class codes are part of a standardized system created by the National Motor Freight Traffic Association (NMFTA). They help carriers, shippers, and brokers determine pricing, liability, and handling requirements for LTL shipments.

Every commodity shipped via LTL is assigned a code ranging from Class 50 to Class 500. Lower classes are typically reserved for dense, durable freight that is inexpensive to ship, while higher classes apply to lighter, bulkier, or more fragile items that require special care.

How Freight Classes Are Determined

Freight class isn’t random—it’s based on four main factors:

  • Density: Freight that is compact and heavy for its size will usually fall into a lower (cheaper) class.

  • Stowability: Items that are easy to load and don’t have restrictions (like hazardous materials or odd shapes) are more affordable to ship.

  • Handling: If freight requires special equipment or is awkward to move, it will be assigned a higher class.

  • Liability: Fragile, perishable, or high-value items come with greater risk and therefore cost more to transport.

These factors combine to give carriers a standard way of pricing freight and ensuring fair rates across the board.

Why Freight Class Codes Matter

For shippers, getting the freight class wrong can mean more than just confusion—it can mean unexpected charges. If the carrier inspects your shipment and determines that it was misclassified, they can reclassify it and issue an adjustment fee. That’s why understanding your freight class upfront is critical to keeping costs under control.

Common Freight Classes

While freight class covers a wide range of items, here are a few examples to illustrate:

  • Class 50: Bricks, tile, or dense industrial goods.

  • Class 100: Machinery or automotive parts.

  • Class 250: Furniture, appliances, or lighter consumer goods.

  • Class 500: Very bulky, fragile, or low-density items such as ping pong balls or large display props.

How to Find Your Freight Class

There are a few ways to determine the correct freight class for your shipment:

  • Use the NMFC directory, which lists commodities and their corresponding class codes.

  • Work with your carrier or broker to confirm classification.

  • Calculate density and compare it against standard charts to estimate the right class.

Getting this right ensures accurate quotes, fewer disputes, and smoother shipping operations.

Bottom Line

Freight class codes are the backbone of LTL pricing. By standardizing shipments across density, stowability, handling, and liability, they give carriers and shippers a clear framework for cost and risk. Understanding your freight class—and making sure it’s correct—can save money, reduce surprises, and keep your supply chain running smoothly.