Freight Class Guide:
NMFC Classes Explained

What Is a Freight Class?

Freight class is a standardized classification system used by LTL carriers to categorize shipments and determine pricing. It's established by the National Motor Freight Traffic Association (NMFTA) and published in the National Motor Freight Classification (NMFC) — the industry's definitive guide to how different types of cargo should be rated.

There are 18 freight classes ranging from Class 50 (the cheapest to ship) to Class 500 (the most expensive). Your freight class directly impacts your LTL rate — a Class 500 shipment can cost 5–10x more to ship per pound than a Class 50 shipment of the same weight.

The Four Factors That Determine Freight Class

Freight class is determined by four characteristics of your shipment. Carriers evaluate all four to assign the appropriate NMFC class:

1. Density

Density is the most important factor — it's the weight of your shipment divided by its cubic footage. Denser freight (more weight per cubic foot) gets a lower, cheaper class. Light, bulky freight gets a higher, more expensive class.

Formula: Density (lbs/cubic ft) = Weight (lbs) ÷ [Length × Width × Height (inches) ÷ 1,728]

2. Stow-ability

Can your freight be stacked with other cargo? Oddly shaped items, hazardous materials, or freight requiring special orientation (e.g., "this side up") is harder to stow and may receive a higher class.

3. Handling

How difficult is it for terminal workers to move your freight? Heavy single pieces, fragile items, or hazardous materials require extra care and equipment — which raises the class.

4. Liability

High-value, perishable, or theft-prone freight carries greater liability risk for the carrier, which is reflected in a higher freight class and corresponding rate.

Complete Freight Class Chart

Use this reference chart to understand what density range and commodity types correspond to each NMFC class.

Class	Density (lbs/cu ft)	Example Commodities
50	50+ lbs	Cement, steel bolts, hardwood flooring, heavy machinery parts
55	35–50 lbs	Bricks, mortar, hardwood lumber, cast iron products
60	30–35 lbs	Car accessories, canned food, steel wire
65	22.5–30 lbs	Car parts, bottled beverages, machinery
70	15–22.5 lbs	Engines, food products, auto parts
77.5	13.5–15 lbs	Tires, bathroom fixtures, appliances
85	12–13.5 lbs	Crated machinery, cast iron stoves, transmissions
92.5	10.5–12 lbs	Computers, monitors, refrigerators
100	9–10.5 lbs	Boat covers, canvas, wine cases, caskets
110	8–9 lbs	Cabinets, framed artwork, table saws
125	7–8 lbs	Small appliances, auto glass, vending machines
150	6–7 lbs	Auto sheet metal, bookcases, assembled furniture
175	5–6 lbs	Clothing, couches, stuffed furniture
200	4–5 lbs	Sheet metal parts, auto body parts, aluminum
250	3–4 lbs	Mattresses, plasma TVs, bamboo furniture
300	2–3 lbs	Wood cabinets, flat-screen TVs, kayaks
400	1–2 lbs	Deer antlers, ping pong balls, light fixtures
500	Less than 1 lb	Bags of gold dust, feathers, low-density foam

How to Calculate Your Freight Density

Follow these steps to calculate your shipment's density and find the right freight class:

• Measure your shipment's length, width, and height in inches (include any pallet or packaging)
• Multiply length × width × height to get total cubic inches
• Divide by 1,728 to convert to cubic feet
• Divide your shipment weight (in lbs) by the cubic footage to get density
• Match your density to the class chart above

Example Calculation

A palletized shipment measuring 48" × 40" × 48" and weighing 500 lbs:

• Volume: 48 × 40 × 48 = 92,160 cubic inches
• Cubic feet: 92,160 ÷ 1,728 = 53.3 cubic feet
• Density: 500 lbs ÷ 53.3 = 9.4 lbs per cubic foot
• Freight class: Class 100

Common Freight Class Mistakes to Avoid

• Underestimating dimensions — Always measure to the outermost point, including pallet and packaging. Carriers re-measure.
• Guessing the class — If you're unsure, look up the NMFC item number for your specific commodity at nmfta.org or ask your freight broker.
• Ignoring density-based classes — Many commodities now use density-based classification. If your item doesn't have a specific NMFC item number, use the density chart above.
• Not accounting for packaging weight — Include pallet weight in your total. A 40 lb pallet on a 460 lb shipment means you're quoting 500 lbs total.
• Skipping the BOL freight class field — Always declare the class on your Bill of Lading. Missing class declarations give carriers grounds to reclassify at their discretion.

Frequently Asked Questions

What happens if I use the wrong freight class?

If a carrier determines your freight class is incorrect — either through re-measurement at the terminal or upon delivery — they'll issue a reclassification notice and charge you the difference based on the correct class, plus an inspection fee. This can significantly increase your final invoice. When in doubt, ask your broker or use the NMFC lookup tool.

Can I dispute a freight class reclassification?

Yes. If you believe a reclassification is in error, you can dispute it with documentation — original measurements, photos, weight tickets, or NMFC item references. Work through your broker or the carrier's claims department. Resolution can take 2–6 weeks.

Do all carriers use the same freight class system?

Yes — all LTL carriers in the US use the NMFC classification system as the standard. However, carriers may apply different base rates to each class, which is why comparing quotes across multiple carriers for the same freight class and lane is essential for finding the best price.

Is there a way to lower my freight class?

The best way to lower your freight class is to increase your shipment's density — repackage into smaller, denser boxes, remove excess packaging, or consolidate multiple boxes onto a single pallet. A denser shipment gets a lower class and a lower rate per pound.