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Freight class is a standardized rating system developed by the National Motor Freight Traffic Association (NMFTA) that determines how less-than-truckload (LTL) shipments are priced. Established in 1936 with the creation of the National Motor Freight Classification (NMFC), the system assigns a class number from 50 to 500 to every commercial freight commodity based on four characteristics: density, stowability, handling ease, and liability. Lower class numbers represent denser, easier-to-handle, lower-liability goods that are cheaper to ship per pound; higher class numbers represent lighter, more fragile, or harder-to-handle commodities that cost more. Density is by far the most important factor in freight class determination — most commodities are classified primarily on the basis of their density in pounds per cubic foot. The NMFC publishes a density-to-class table that maps specific density ranges to class assignments: freight denser than 50 lb/ft³ is Class 50 (the cheapest), while freight lighter than 1 lb/ft³ is Class 400 or 500 (the most expensive). This density-based pricing reflects the economic reality that a carrier filling a trailer with extremely light goods cannot earn adequate revenue from weight-based pricing alone. Understanding and correctly calculating freight class is essential for anyone shipping LTL freight. Incorrect class assignment — either deliberate or accidental — results in reclassification charges at delivery when the carrier's dock staff re-measures and re-weighs the shipment. Reclassification fees typically add $75–$300 to the freight bill and may arrive weeks after delivery, creating cash flow and reconciliation headaches. Shippers who consistently misclassify freight risk losing carrier relationships or being required to prepay all shipments. The freight class system has faced criticism for its complexity — over 20,000 commodity descriptions in the NMFC — and some carriers have shifted to simplified density-based pricing (sometimes called 'freight all kinds' or FAK pricing) that bypasses class entirely. Under FAK, all freight is priced based on density alone, which simplifies billing but may disadvantage shippers of high-density goods who would otherwise qualify for Class 50 or 55 pricing.
Freight Class Determination: Step 1 — Calculate Density: Volume (ft³) = (Length × Width × Height in inches) ÷ 1,728 Density (lb/ft³) = Shipment Weight (lb) ÷ Volume (ft³) Step 2 — Map Density to NMFC Class: Density (lb/ft³) → Freight Class ≥ 50 → Class 50 35–49.9 → Class 55 30–34.9 → Class 60 22.5–29.9 → Class 65 15–22.4 → Class 70 13.5–14.9 → Class 77.5 12–13.4 → Class 85 10.5–11.9 → Class 92.5 9–10.4 → Class 100 8–8.9 → Class 110 7–7.9 → Class 125 6–6.9 → Class 150 5–5.9 → Class 175 4–4.9 → Class 200 3–3.9 → Class 250 2–2.9 → Class 300 1–1.9 → Class 400 < 1 → Class 500 Step 3 — Calculate LTL Rate: LTL Cost = Tariff Base Rate × (1 − Discount%) + Fuel Surcharge% + Accessorials
- 1Measure the shipment dimensions — for palletized freight, measure the full pallet footprint (typically 48×40 inches) and the stacked height including pallet; for non-palletized freight, measure the actual dimensions of the cargo unit.
- 2Calculate the volume in cubic feet: multiply length × width × height in inches and divide by 1,728 (cubic inches per cubic foot).
- 3Weigh the complete shipment including all packaging, pallets, and bands — use a floor scale or pallet jack scale for accuracy, as estimates often understate actual weight.
- 4Divide the shipment weight by the volume to get density in pounds per cubic foot — this single number determines the base freight class for most commodity types.
- 5Look up the commodity's NMFC item number in the NMFC classification system or use the density table to find the applicable freight class — some commodities have fixed classes regardless of density (e.g., new furniture is always Class 125; automobile parts have specific NMFC items).
- 6Verify any special classification rules: some NMFC items require specific packaging types (e.g., 'in boxes' vs. 'on pallets') and may assign different classes based on packaging method.
- 7Enter the class, weight, and lane (origin/destination zip codes) into a carrier rate quote system or freight broker portal to obtain the LTL rate — apply negotiated discount percentage to get the net linehaul rate.
Dense industrial equipment at 15 lb/ft³ qualifies for Class 70 — a mid-range class. Class 70 LTL rates are relatively affordable; this density reflects compact machinery or packaged manufactured goods.
A queen mattress is light relative to its volume — a classic high-class commodity. Class 400 rates can be 6–8× Class 70 rates per pound, making mattress shipping extremely expensive and driving the economics of white-glove delivery services.
Auto parts have specific NMFC item numbers that may assign a fixed class or a class based on density. At 15 lb/ft³ with NMFC auto parts classification, Class 65 typically applies — slightly better than the pure density table would suggest.
Steel rebar is extremely dense — 100 lb/ft³ easily exceeds the 50 lb/ft³ threshold for Class 50. At Class 50, LTL rates per hundred pounds (CWT) are the lowest in the system. High-density metals always qualify for Class 50.
Freight brokers use freight class calculators to instantly quote LTL rates for shipper clients, inputting commodity type, weight, and dimensions to generate class-based rate comparisons across multiple carrier tariffs.
Manufacturers use freight class analysis during product packaging design to determine whether a packaging change (e.g., reducing box height by 3 inches) would shift the freight class from 100 to 85, reducing LTL shipping costs on all outbound shipments.
Third-party logistics (3PL) providers build freight class verification into their shipping workflows to flag potential reclassification risks before shipments leave the dock, reducing post-delivery freight bill adjustments.
Supply chain managers use freight class benchmarks when evaluating new product lines — understanding that a new bulky low-density product will ship at Class 200+ allows accurate landed cost modeling before product launch.
Some NMFC items have fixed freight classes that override the density
Some NMFC items have fixed freight classes that override the density calculation entirely — for example, new furniture is always Class 125 regardless of how dense it is, and certain types of machinery have item-specific classes. For these commodities, looking up the specific NMFC item number is essential; using the density table alone will produce the wrong class.
Pallets with mixed freight (multiple commodity types) are classified based on
Pallets with mixed freight (multiple commodity types) are classified based on the highest-class item on the pallet unless the commodities are shipped as a single package or crate. Shippers consolidating mixed goods onto pallets should be aware that one high-class item (e.g., a pillow) mixed with Class 50 freight will reclassify the entire pallet to the pillow's class. Separating commodities onto separate shipments can reduce total freight cost.
Density-based pricing (DBP), offered by carriers like XPO Logistics and Estes
Density-based pricing (DBP), offered by carriers like XPO Logistics and Estes Express, prices freight based purely on density without reference to NMFC class. Under DBP, the rate is determined by a density-to-rate table negotiated in the contract. DBP eliminates class disputes but requires accurate density measurement at origin — typically using inline dimensioning scanners on the dock.
| Freight Class | Density (lb/ft³) | Example Commodities | Relative Rate vs. Class 100 |
|---|---|---|---|
| Class 50 | ≥ 50 | Steel, cast iron, hardwood flooring | ~40% |
| Class 65 | 22.5–29.9 | Car accessories in boxes, bottled beverages | ~60% |
| Class 85 | 12–13.4 | Crated machinery, cast iron stoves | ~75% |
| Class 100 | 9–10.4 | Wine in bottles, car covers, furniture parts | 100% (baseline) |
| Class 125 | 7–7.9 | Small household appliances, auto glass | ~130% |
| Class 150 | 6–6.9 | Auto sheet metal, boats | ~160% |
| Class 200 | 4–4.9 | Aircraft parts, aluminum tables | ~220% |
| Class 300 | 2–2.9 | Wood cabinets, tables (knocked down) | ~330% |
| Class 400 | 1–1.9 | Ping pong balls, mattresses | ~500% |
| Class 500 | < 1 | Low density bags, gold dust | ~700%+ |
How many freight classes are there?
There are 18 freight classes: 50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400, and 500. The numbering is not sequential by equal intervals — the fractional classes (77.5, 92.5) reflect historical density band adjustments. Class 50 is the cheapest (densest goods) and Class 500 is the most expensive (lightest, most problematic goods). Class 100 is considered the 'median' and is often used as the baseline for rate comparisons.
What happens if my freight is reclassified at delivery?
Reclassification occurs when a carrier's dock crew re-measures and re-weighs your shipment at destination and determines that the freight class you declared was incorrect. The carrier then bills you at the higher, correct class rate. Reclassification charges include the rate difference plus a reclassification fee of $75–$300 on top. Reclassification bills typically arrive 1–3 weeks after delivery, creating unexpected costs. Repeated reclassifications may result in the carrier requiring pre-payment or declining your freight.
What is FAK (Freight All Kinds) pricing?
FAK (Freight All Kinds) is a simplified LTL pricing structure where a carrier applies a single negotiated freight class to all shipments within a defined density range, regardless of the actual NMFC class. For example, a FAK agreement might price all freight with density above 10 lb/ft³ as Class 70, even if some items would normally classify as Class 85 or 100. FAK is popular with high-volume shippers because it simplifies invoicing and eliminates reclassification disputes. It's negotiated as part of carrier contracts.
Is freight class the same as shipping class?
Freight class (NMFC class) is specifically the LTL classification system for motor freight carriers. It is different from postal/parcel service weight-based tiers (like USPS mail classes) and different from FTL pricing, which doesn't use class at all. Freight class applies specifically to LTL truck shipments. Air freight uses dimensional weight. Ocean freight uses container-based (FCL) or volumetric-based (LCL) pricing. Only LTL motor freight uses the 18-class NMFC system.
Can I look up freight class myself without a broker?
Yes. The NMFC publishes a subscription database (ClassIT Online) that allows you to search commodity descriptions and find the applicable NMFC item number and class. The NMFTA website provides access. Many free online tools and carrier websites offer freight class lookups based on commodity type and density. For most common commodities, the density-to-class table provides a reliable estimate — only for complex or regulated commodities do you need to consult the full NMFC item database.
Which freight class is most common?
Class 50 and Class 55 are most common by weight volume (dense commodities like metals, machinery, and building materials dominate freight by tonnage). Class 70 and Class 100 are the most commonly cited 'typical' classes for general manufactured goods. By number of LTL shipments, Class 50–100 covers the majority of commercial freight. Classes above 200 are relatively uncommon and represent specialty items — antiques, artwork, extremely fragile goods, or very light bulky products.
How do I reduce my freight class?
The most effective strategies are: increase density by consolidating freight onto fewer pallets with tighter stacking, reduce packaging void space to lower volume, use denser packaging materials, palletize loose items to reduce handling-based class adjustments. Some shippers stack multiple SKUs together to achieve higher overall pallet density. If your commodity has multiple NMFC item descriptions that apply, select the one with the lowest class that accurately describes your product and packaging. Never misrepresent freight — it creates legal liability and carrier relationship damage.
Pro Tip
If you frequently ship the same commodities and face reclassification charges, request a binding freight class ruling from your carrier in writing. Many carriers will pre-inspect and issue a written class ruling for recurring freight, eliminating reclassification surprises. Alternatively, negotiate a FAK agreement that covers your typical freight density range at a fixed class — this trades potential upside (lower class on dense shipments) for certainty.
Did you know?
The NMFC contains over 20,000 individual commodity descriptions covering everything from aardvark hides to zucchini. It has been continuously maintained since 1936, with quarterly updates adding new commodities and revising classifications as products evolve. One of the most debated NMFC items in freight circles is 'ping-pong balls' — Class 400 despite weighing practically nothing, reflecting the extreme air-to-product ratio and stowability challenges of shipping hollow plastic spheres.