Freight Class & NMFC Codes: An LTL Shipper Guide

Freight class is the classification system that determines what LTL carriers charge to move your pallet. It runs from class 50 (dense, durable, cheap to ship) to class 500 (light, bulky, fragile, expensive). Get the class wrong and the carrier will reclassify your shipment after the fact and send you a corrected invoice — often weeks later, and almost never in your favor.

If you ship LTL out of South Florida with any regularity, understanding classification is one of the highest-return hours you can spend on your freight program.

What determines freight class

Freight classes are assigned under the National Motor Freight Classification (NMFC), maintained by the National Motor Freight Traffic Association. Classification is based on four characteristics:

1. Density — pounds per cubic foot. The dominant factor for most commodities.
2. Stowability — how easily the freight loads alongside other freight. Oversized, oddly shaped or hazardous items score worse.
3. Handling — whether special equipment or care is needed.
4. Liability — value per pound, and susceptibility to damage or theft.

Many commodities have a fixed NMFC item number and class regardless of density. Others are “density-based,” meaning the class is determined by calculating pounds per cubic foot and reading off a density scale. Knowing which category your product falls into is the first thing to establish.

How to calculate density

Measure the fully packaged, palletized shipment — including the pallet and any overhang.

Cubic feet = (length × width × height in inches) ÷ 1,728
Density = total weight in pounds ÷ cubic feet

Example: a pallet measuring 48″ × 40″ × 50″ is 55.6 cubic feet. At 700 lbs total, density is about 12.6 pounds per cubic foot.

Higher density generally means a lower class and a lower rate. This is why pallet building is a freight cost decision, not just a warehouse decision — a pallet stacked to 50 inches instead of 70 inches with the same weight moves into a better density bracket.

A note on the 2025 NMFC restructuring

The NMFTA has been implementing a significant overhaul of the classification system, consolidating many commodity-specific listings into a standardized density-based scale. The practical effect for shippers is that accurate dimensions matter more than they used to, and classes you have relied on for years may have changed.

If you have not reviewed your classifications recently, do it. Because the rollout has been phased and details continue to evolve, confirm current classifications with your carrier or a licensed freight broker rather than relying on an internal table built years ago.

What reclassification actually costs you

When freight arrives at a terminal, carriers increasingly run it through automated dimensioning equipment that captures exact dimensions and weight in seconds. If the numbers do not match your bill of lading, you get:

• A reclassification and a corrected invoice, frequently well above the original quote.
• A reweigh or inspection fee on top.
• Accessorial charges you did not anticipate.
• An invoice arriving weeks later, after you have already billed your customer.

The margin damage is worse than the fee itself, because you have usually already quoted your customer a freight cost you can no longer recover.

How to stop getting reclassified

1. Measure the real pallet. Actual dimensions after wrapping, including overhang and any protruding edges. Round up, not down.
2. Weigh the real pallet. Certified scale, not an estimate from a spec sheet.
3. Record dimensions and weight at load-out. Your warehouse should capture this per shipment as standard practice, and it should flow onto the BOL automatically.
4. List the correct NMFC item number. Class alone is not enough; carriers work from the item number.
5. Build tighter pallets. Eliminating dead air raises density and can lower your class outright.
6. Review classifications annually. Packaging changes, and so does the NMFC.

Where the warehouse makes or breaks this

Every input to freight class is generated on the warehouse floor. If your 3PL builds inconsistent pallets, does not dimension and weigh outbound freight, or transcribes numbers by hand onto the BOL, you will get reclassified — no amount of upstream analysis prevents it.

What a well-run outbound operation looks like: pallets built to a documented standard per SKU, dimensions and certified weight captured at load-out, that data flowing directly into the BOL, and photos retained for dispute evidence. Our guide to warehouse KPIs and 3PL scorecards covers how to write this into a provider agreement.

If you are still deciding between shipping modes, our comparison of LTL versus FTL for Miami distribution covers the volume thresholds where full truckload becomes the better answer — and one advantage of FTL is that freight class stops mattering entirely.

Frequently asked questions

What is freight class and why does it matter?

Freight class is a standardized classification, ranging from 50 to 500, that LTL carriers use to price shipments. It is determined under the National Motor Freight Classification based on density, stowability, handling and liability. Lower classes generally cost less to ship. Declaring the wrong class typically results in the carrier reclassifying the shipment and issuing a corrected, higher invoice.

How do I calculate freight density?

Multiply the packaged shipment’s length, width and height in inches, then divide by 1,728 to get cubic feet. Divide the total weight in pounds by that cubic footage to get pounds per cubic foot. Always measure the fully wrapped pallet including the pallet itself and any overhang.

What happens if I use the wrong freight class?

Carriers routinely dimension and weigh freight at the terminal. If your bill of lading does not match, the shipment is reclassified and you receive a corrected invoice, usually along with an inspection or reweigh fee. These corrections often arrive weeks after delivery, after you have already invoiced your own customer, which makes the cost difficult to recover.

Ship LTL out of Miami with accurate paperwork

Go Warehouse builds and documents outbound pallets to a consistent standard, capturing dimensions and weight at load-out so your bills of lading match what the carrier measures. Learn more about our warehousing and distribution services, or request a quote to review your outbound program.