If you’ve shipped goods that didn’t require a full truck, you’ve probably used LTL shipping. One of the key concepts in this cargo shipping method is freight class. It impacts how much you pay, how your freight is handled, and even how it's insured. In this guide, we’ll break down what freight class means in LTL shipping, how it's calculated, and how you can avoid common mistakes.

What is LTL Shipping

LTL (Less-than-Truckload) shipping is used when a shipment doesn’t fill an entire trailer. Instead of paying for unused space, multiple shippers share the same truck and only pay for the space their cargo occupies. This makes LTL ideal for:

  • Palletized shipments weighing between 150 and 15,000 pounds
  • Regular small-scale deliveries
  • Companies looking to reduce freight costs without sacrificing speed

It differs from Full Truckload (FTL) shipping, which reserves the entire trailer for one customer, regardless of how full it is.

What Does Freight Class Mean in LTL Shipping

Freight class is a standardized way to categorize different types of freight, managed by the National Motor Freight Traffic Association (NMFTA). The classification system is known as NMFC (National Motor Freight Classification), and it assigns a class between 50 and 500 to every commodity. That class directly influences your shipping cost, how the freight is handled, and the carrier's liability.

In general:

  • Lower classes (50–85) mean the freight is dense, durable, and easy to ship — these are the cheapest to move.
  • Higher classes (150–500) are reserved for freight that is lightweight, fragile, bulky, or hazardous — these cost more to ship.

Why Freight Class Matters

The class you assign to your shipment isn’t just for paperwork; it affects almost every aspect of the shipping process:

  • Price: Carriers use freight class to calculate rates. A small misclassification can lead to major cost differences.
  • Handling: Higher-class freight may require more care, special equipment, or dedicated space.
  • Liability: High-value or fragile goods increase the carrier’s risk, which is reflected in the class and the insurance terms.

How is LTL Freight Class Determined

There are four primary factors that influence your freight’s class: density, stowability, handling, and liability. Let’s look at each one.

1. Density

This is the most critical factor. Density is calculated by dividing your shipment’s weight by its volume in cubic feet.

Formula: Density = Weight (lbs) ÷ (L × W × H in inches ÷ 1,728)

Here’s a quick reference to show how density affects class:

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So, if you’re shipping something compact and heavy — like machine parts — you’ll likely fall into a low freight class, which keeps your costs down. On the other hand, something large but light, like a foam mattress, would likely be classified at a much higher level.

2. Stowability

Stowability reflects how easily freight can be loaded and stored with other items in a truck. Items that are oddly shaped, long, hazardous, or non-stackable may take up more space than their volume suggests.

Carriers consider freight with:

  • Odd shapes (like long pipes or machinery arms)
  • Hazardous materials
  • Temperature requirements
    as less stowable and will assign a higher freight class accordingly.

3. Handling

Handling evaluates how much effort is required to move the freight from origin to destination. If your shipment is palletized and can be moved by a forklift, handling is considered easy. But if it’s fragile, oddly sized, or requires special tools, your freight will move into a higher class.

Challenging freight might include:

  • Large glass panels;
  • Delicate electronics;
  • Live plants or animals (special care);

4. Liability

Liability refers to the probability of loss or damage and the value of the shipment. Higher liability increases the class because it raises the carrier’s risk.

Freight with high liability typically includes:

  • Pharmaceuticals;
  • Jewelry and expensive electronics;
  • Perishable or flammable goods;

NMFC Codes and Example Classifications

Every product has a designated NMFC code that links to a freight class. These codes are used universally across carriers and help avoid disputes or confusion.

Here are a few sample commodities and how they’re classified:

It’s always smart to confirm NMFC codes with your carrier or freight broker before booking a shipment.

Real-World Example: Comparing Two Shipments

Let’s say you have two shipments:

  • Shipment A: A tightly packed pallet of steel gears weighing 1200 lbs and occupying 24 cubic feet
    Density: 50 lbs/ft³ → likely class: 55
  • Shipment B: Lightweight assembled shelving weighing 400 lbs, using up 60 cubic feet
    Density: 6.7 lbs/ft³ → likely class: 175–200

Despite being heavier, Shipment A will cost less to ship due to its high density and ease of handling.

How to Accurately Classify Your LTL Freight

To avoid surprises, follow these best practices:

  • Measure and weigh your shipment precisely, including packaging;
  • Calculate density using accurate dimensions;
  • Use a freight class calculator or check with the NMFC database;
  • Label your items properly, especially if they’re hazardous or fragile;
  • Partner with a freight broker or 3PL who understands the system;

Common Mistakes to Avoid

Getting freight class wrong can lead to unexpected fees or delays. Here are common errors and how to avoid them:

  • Guessing the class: Always confirm through NMFC or with your carrier;
  • Underestimating dimensions: Include all packing material in your measurements;
  • Ignoring liability: High-value or perishable items require correct classification;
  • Trying to cheat the system: Misclassification may lead to audits and penalties;

Reclassifications and Freight Audits

Carriers are equipped to re-measure, weigh, and reclassify shipments. If your stated class is incorrect, you may face:

  • Extra fees;
  • Delivery delays;
  • Disputes with the carrier;

To protect yourself:

  • Keep digital records of dimensions and weight;
  • Take photos before shipping;
  • Always document the NMFC code used;

The Future of Freight Classification

Technology is improving how freight is classified. Many warehouses now use automated dimensioners that scan and weigh freight instantly. In the near future, AI-driven systems may assign classes based on cargo type, dimensions, and historical data — reducing human error and simplifying pricing.

Conclusion

Freight class is more than a shipping detail — it’s a pricing and logistics tool that determines how your cargo moves and how much you pay. Understanding how class is calculated, especially based on density, stowability, handling, and liability, allows you to avoid costly mistakes. Whether you’re a small business shipping a few pallets or a large operation managing complex supply chains, knowing your freight class helps you ship smarter, faster, and more affordably.

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