What Is Freight Class? A Plain-English Guide

If you have ever pulled an LTL quote, you have met freight class — that 50-to-500 number the carrier wants before they will price your shipment. Get it right and you pay a fair rate. Get it wrong and you either overpay up front or get hit with a re-class fee after the carrier weighs and measures your freight at the dock. This guide explains what freight class actually is, the 18 classes, how it is decided, and why it is the most important number on your bill of lading.

What freight class means

Freight class is a standardized way to group shipments so that any LTL carrier in North America prices comparable freight the same way. It is set by the National Motor Freight Classification (NMFC), a rulebook maintained by the National Motor Freight Traffic Association (NMFTA). Every shipment is sorted into one of 18 classes, numbered from 50 (the cheapest to ship) up to 500 (the most expensive).

The logic is simple once you see it: the number reflects how hard the freight is to transport. A low class means dense, durable, stackable goods that pack efficiently into a trailer and rarely get damaged. A high class means light, bulky, fragile or valuable goods that waste trailer space or carry more risk. The harder your freight is to haul, the higher the class — and the more it costs per pound.

The 18 freight classes at a glance

There are exactly 18 classes. Here is the full scale, with the kind of freight that typically lands in each band:

The density figures are a guide, not a hard rule — the official density breakpoints vary slightly by commodity, and some goods carry a fixed class regardless of how dense they are. To see the full density-to-class scale and look up your number, use the freight class calculator or browse the freight class & NMFC reference.

How freight class is determined: the four NMFC factors

The NMFC assigns class on four characteristics. For most everyday shipments, density does the heavy lifting, but the other three can move the number — especially for awkward, fragile or high-value goods.

1. Density

Density is weight per cubic foot, and it is the dominant factor for the majority of commodities. You calculate it by dividing your shipment’s total weight (in pounds) by its total volume (in cubic feet). Higher density pushes you toward a lower, cheaper class. This is why how you package and palletize matters so much — a tighter, denser load can drop you a class or two.

2. Stowability

How easily the freight loads alongside other shipments. Oversized, oddly shaped, hazardous or non-stackable items waste trailer space or can’t share a load, so they rate higher.

3. Handling

How much care the freight needs in transit. Fragile goods, items that can’t be forklifted, or anything requiring special equipment is harder to move and pushes the class up.

4. Liability

The risk of damage, theft or the freight damaging adjacent shipments. High-value or perishable goods carry more liability for the carrier, which raises the class.

Two paths exist for getting a final class. Density-based commodities are rated purely on the density scale above. Fixed-class commodities have a class hard-coded to their NMFC item number — for example, a specific machinery or produce line item — no matter the density. The freight class calculator handles the density math; for fixed-class goods, look up the commodity in the NMFC reference.

NMFC vs. freight class: clearing up the confusion

People use these terms interchangeably, but they are not the same thing:

• NMFC is the classification system and rulebook — thousands of commodity listings, each with an item number (and often sub-numbers) and the rules for assigning a class.
• NMFC number is the specific code for your commodity within that book (e.g. an item number for “machinery, NOI”).
• Freight class is the resulting 50–500 figure that the NMFC rules produce for your shipment.

On the bill of lading you typically list both the NMFC item number and the freight class. The NMFC number tells the carrier exactly what the commodity is; the class tells them how to price it.

How to calculate your freight class step by step

For a standard density-based shipment, the process is short:

1. Measure the loaded, packaged shipment. Length, width and height in inches — including the pallet and any overhang. Round up to the outermost points.
2. Find the volume in cubic feet. Multiply length × width × height in inches, then divide by 1,728 (the number of cubic inches in a cubic foot).
3. Weigh it. Use the total weight of the packaged shipment, pallet included.
4. Divide weight by volume. That is your density in pounds per cubic foot.
5. Match the density to the class. Look the figure up on the scale to get your class.

Example: a pallet measuring 48 × 40 × 48 inches is 92,160 cubic inches, or 53.3 cubic feet. If it weighs 900 lb, the density is roughly 16.9 lb/ft³ — which lands it around Class 70. Rather than do this by hand for every shipment, drop the dimensions and weight into the freight class calculator and it returns the class instantly. If you ship mixed or low-density freight, the freight density calculator shows exactly how close you are to the next class break.

Why freight class is the biggest lever on your LTL cost

Class, weight and lane drive an LTL quote — and of the three, class is the one you have the most control over. The same 900-lb pallet on the same lane can cost dramatically more at Class 250 than at Class 70, because the carrier’s base rate per hundredweight climbs with the class. That is why two shipments of identical weight, going to the same place, can carry very different price tags.

There are two practical reasons to nail it:

• Avoid re-class fees. If you under-declare the class, the carrier re-weighs and re-measures at the terminal, corrects the class, and bills the difference plus a fee. Accurate classification up front keeps your quoted price honest.
• Package to a lower class. Because density drives class, tighter packaging, smarter palletizing, and reducing wasted air can legitimately move you to a cheaper class. It is one of the most reliable ways to cut LTL spend — see our guide on lowering your LTL freight costs.

Class only applies to LTL, where your freight shares a trailer and the carrier needs a fair way to price each slice. Book a full truck and class falls away — you pay a flat lane rate instead. If you are weighing the two, our breakdown of LTL vs. FTL shows where the crossover usually lands. And because a light, bulky box can be billed on its size rather than its weight, it is worth understanding dimensional weight alongside class.

The bottom line

Freight class is a 50-to-500 shorthand for how hard your LTL shipment is to haul, set mainly by density and fine-tuned by stowability, handling and liability under the NMFC rules. Knowing your class — and packaging to improve it — is the difference between a fair rate and an inflated one. Calculate it before you quote: run the loaded pallet through the freight class calculator, then send the same shipment to several carriers with the freight quote builder so the numbers come back comparable.