If you ship LTL freight, the NMFC code you put on your bill of lading determines how much you pay. Get the code wrong and you face reclassification charges, freight bill corrections, and - if you're a broker - an awkward call to your customer explaining why the invoice is 40% higher than the quote. Yet most shippers treat NMFC lookup as a guessing game, relying on what they've "always used" without verifying it against the actual classification rules.
This guide covers exactly how the NMFC system works, how to use the classification database, the 4-factor test carriers apply when they inspect your freight, and worked examples for common commodity categories that generate the most disputes.
The National Motor Freight Classification (NMFC) is a freight classification system published and maintained by the National Motor Freight Traffic Association (NMFTA), a nonprofit based in Alexandria, Virginia. The NMFTA is funded by carrier memberships and has been publishing the classification tariff since the 1930s. The current NMFC is updated regularly - new commodity items are added, existing classifications are revised, and density thresholds are adjusted based on carrier data.
The NMFC tariff is a subscription document. You cannot freely access a complete, searchable version online. The NMFTA sells annual subscriptions to the ClassIT online tool, which provides a searchable database of all current NMFC items. Individual subscriptions cost several hundred dollars per year. Many shippers, brokers, and 3PLs subscribe to ClassIT or use a TMS that includes licensed NMFC data.
Carriers have their own copies of the NMFC and use it when they inspect and reclassify freight at their terminals. The carrier's version is always current. If yours is outdated, you may be classifying freight under a revision that no longer exists.
Note: Some carriers have moved to density-based pricing (DBP) that bypasses the NMFC classification system entirely. Under DBP, the rate is calculated purely from the shipment's density (weight divided by cubic feet), with no class lookup required. Not all carriers offer DBP, and it is not available on all lanes.
The NMFC system has 18 freight classes. Classes are numbered at specific intervals: 50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400, and 500. Class 50 is the least expensive to ship (dense, stable freight), and class 500 is the most expensive (very light or difficult freight).
Many commodities have a density-based class table in the NMFC - meaning the class assigned depends on the actual pounds-per-cubic-foot density of the shipment. Other commodities have a fixed class regardless of density, based on the other three factors in the NMFC test.
| Freight Class | Density (lbs/cu ft) | Example Commodities |
|---|---|---|
| Class 50 | 50+ lbs/cu ft | Sand, steel bars, heavy machinery parts |
| Class 55 | 35-50 lbs/cu ft | Hardwood flooring, bricks, cast iron |
| Class 60 | 30-35 lbs/cu ft | Car accessories, tools, stone |
| Class 65 | 22.5-30 lbs/cu ft | Car parts, bottled water, books |
| Class 70 | 15-22.5 lbs/cu ft | Food items, auto engines, forklifts |
| Class 77.5 | 13.5-15 lbs/cu ft | Tires, bathroom fixtures, cables |
| Class 85 | 12-13.5 lbs/cu ft | Crated machinery, cast iron stoves |
| Class 92.5 | 10.5-12 lbs/cu ft | Computers, monitors, refrigerators |
| Class 100 | 9-10.5 lbs/cu ft | Boat covers, wine cases, caskets |
| Class 110 | 8-9 lbs/cu ft | Cabinets, framed art, table saws |
| Class 125 | 7-8 lbs/cu ft | Small household appliances, displays |
| Class 150 | 6-7 lbs/cu ft | Auto sheet metal, bookcases, mattresses |
| Class 175 | 5-6 lbs/cu ft | Clothing, couches, stuffed animals |
| Class 200 | 4-5 lbs/cu ft | Sheet metal, aircraft parts, aluminum tables |
| Class 250 | 3-4 lbs/cu ft | Bamboo furniture, mattresses boxed, plasma TVs |
| Class 300 | 2-3 lbs/cu ft | Wood cabinets, tables (unassembled) |
| Class 400 | 1-2 lbs/cu ft | Deer antlers, ping pong balls |
| Class 500 | Less than 1 lb/cu ft | Gold dust, bags of air (test materials) |
Density is the primary factor for most commodity classifications. Here is the standard calculation:
Example: A pallet of industrial pumps that measures 48" x 48" x 60" and weighs 800 lbs.
Tip: Always measure the actual packaged dimensions, not the product dimensions. A piece of machinery that measures 30" x 30" x 36" in its crate may be only 20" x 20" x 24" bare. The carrier measures the packaged shipment on their dock.
Density alone does not determine freight class for every commodity. The NMFC classification rules are based on four factors. Each factor can push the classification up or down relative to what density alone would suggest.
As described above. Dense freight is cheaper to ship because it fills trailers efficiently and generates more revenue per cubic foot for the carrier. Light, bulky freight takes up trailer space without contributing proportional weight, so it gets classified at a higher (more expensive) class.
Can the freight be loaded safely with other freight? Items that cannot be stacked (top-heavy, fragile, or irregularly shaped) reduce the carrier's ability to load the trailer efficiently. Freight that must be loaded by itself (hazmat, items requiring dedicated floor space) carries a stowability penalty. Freight that is easily stackable and standard-pallet-sized gets the most favorable stowability rating.
How difficult is the freight to handle at pickup, transfer, and delivery? Freight that requires special equipment (long items, oversized pallets, awkward shapes) or extra labor (loose cartons that need to be stacked, fragile items requiring special care) is more expensive for the carrier to move. The NMFC reflects this in a higher class for difficult-handling commodities.
What is the carrier's exposure if the freight is lost or damaged? High-value, easily pilferable, or perishable commodities carry higher liability for the carrier. Electronics, jewelry, pharmaceuticals, and temperature-sensitive food products all attract higher liability ratings. A commodity classified at class 400 for liability reasons may have a density that would otherwise put it at class 100.
If you have a ClassIT subscription, you search by commodity name or keyword. The database returns matching NMFC items with their item numbers and class assignments. An NMFC item number looks like this: NMFC 112480 with sub-items like 112480-01, 112480-02, etc., representing different packaging types or density bands for the same commodity.
The correct process for looking up a commodity is:
Consumer electronics are among the most frequently reclassified commodities in LTL freight. The NMFC classifies most electronics in the class 92.5-125 range when properly packaged in their original manufacturer packaging. However, "electronics" is not an NMFC description - you need to specify whether you're shipping laptops, monitors, network switches, or televisions, because each has its own item number and potentially different class. The packaging condition matters: items in original OEM packaging often qualify for a lower class than the same items in unpackaged or aftermarket-packaged form.
Furniture is notoriously difficult to classify because it spans a wide density range. A solid hardwood dining table may be class 65-85. A flat-pack (unassembled) particle board table might be class 150-200 because the assembled dimensions are used to calculate density, not the flat-pack dimensions. Upholstered sofas are typically class 125-175 depending on their dimensions and weight. The NMFTA has updated furniture classifications multiple times in the past decade, so always verify against the current tariff.
Most heavy industrial machinery - CNC equipment, presses, pumps, motors - classifies in the 60-100 range due to high density. The critical variable is how it's packaged. Machinery in a proper wooden crate with blocking and bracing classifies better than the same machine on a simple pallet. The crate's dimensions are used for density calculation, so a large crate with minimal interior freight raises the apparent density calculation against you.
Packaged food products range dramatically. Canned goods are class 50-65 (very dense). Snack foods, cereal, and similar low-density packaged goods are class 100-150. Produce shipped in standard containers has its own classification. Temperature-sensitive and perishable foods may carry a higher liability class regardless of density. Always verify whether the food item has a specific NMFC item number before defaulting to a generic food classification.
Manual NMFC lookup is a bottleneck for any organization shipping at volume. ClassIT searches return results that a human must interpret - sub-items must be matched against the actual shipment's density and packaging type. For a shipper with hundreds of SKUs, maintaining a correct internal commodity-to-NMFC mapping is a full-time task as the tariff changes.
API-based NMFC lookup automates this process. A classification API accepts a commodity description and shipment dimensions/weight, queries a current licensed NMFC dataset, and returns the item number and class. When integrated with a TMS or order management system, the BOL is generated with the correct class already populated - no manual lookup, no human error.
This is particularly valuable for brokers and 3PLs who handle diverse commodities from multiple shippers. Rather than trusting shippers to self-classify correctly, the system validates or overrides the declared class at quote time, producing more accurate rates and fewer freight bill corrections. See our guide on how to generate a BOL via API for how NMFC data integrates into the document generation workflow.
Related reading: When your BOL has the correct NMFC code and class, the next step is making sure all other LTL documentation is complete. See our LTL Shipment Documentation Checklist for the full list of required documents.
LTL carriers have the contractual right under their tariffs to inspect, weigh, and measure any shipment. If the carrier's terminal inspector determines that the class you declared does not match the actual commodity and its measured density, they issue a freight bill correction - sometimes called an "inspection charge" or "reclassification charge." This correction invoice adds the difference between what you were quoted and what the correct class rate would have been, plus an inspection fee (typically $35-75).
You can dispute reclassification charges by submitting evidence that your original classification was correct - the NMFC item description, a density calculation showing your measurement, and photographs of the freight. Disputes are resolved by the carrier's claims department. Win rates on reclassification disputes vary; carriers uphold their inspectors' findings in the majority of cases. The best defense is correct classification before tendering.
Systematic reclassification on a shipper's account is a red flag that many carriers track. Repeated disputes can result in the carrier flagging the account for mandatory terminal inspection on every shipment, which adds transit time and handling costs.
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