LTL basics · Freight classification

What is NMFC freight class?

The plain-English guide to the National Motor Freight Classification — the 18 classes, the four factors, how to calculate density, and why a wrong class turns into a reclassification fee.

NMFC freight class is a standardized rating — published by the National Motor Freight Traffic Association (NMFTA) in the National Motor Freight Classification — that groups less-than-truckload (LTL) commodities into 18 classes from 50 to 500. The class is a shorthand for how hard and how expensive a commodity is to move, and it is one of the primary inputs into the LTL rate a carrier quotes. Get it right and the quote holds. Get it wrong and the carrier reweighs the freight at the terminal, reassigns the class, and bills the difference.

If you are new to less-than-truckload freight generally, start with what is LTL freight brokerage for the wider picture; this guide zooms in on the classification system specifically.

Why freight class exists

A full truckload prices roughly on the lane and the truck — one shipper, one trailer, one rate. LTL is different: a carrier consolidates many shippers' freight onto the same trailer, so it needs a fair, repeatable way to price each shipment's share of the trailer. Two pallets that weigh the same can consume wildly different amounts of a trailer and pose wildly different damage risk. Freight class is the industry's answer: a single number that captures how much space, care, and risk a commodity brings, so a carrier can rate thousands of different commodities on a consistent scale.

The 18 freight classes (50–500)

There are 18 classes. Lower classes are dense, durable, and cheap to ship; higher classes are light, bulky, fragile, or high-value and cost more per pound. For density-based commodities, many carriers map density to class using a guideline close to the following (density in pounds per cubic foot):

Class 50 — 50+ lbs/ft³. Dense, durable freight on a standard pallet (e.g. bricks, sand-like bagged goods).
Class 55 — 35–50 lbs/ft³ (e.g. bagged cement, hardwood flooring).
Class 60 — 30–35 lbs/ft³ (e.g. car accessories, dense machined parts).
Class 65 — 22.5–30 lbs/ft³ (e.g. bottled beverages, books).
Class 70 — 15–22.5 lbs/ft³ (e.g. auto engines, food items).
Class 77.5 — 13.5–15 lbs/ft³ (e.g. tires, bathroom fixtures).
Class 85 — 12–13.5 lbs/ft³ (e.g. crated machinery, cast-iron stoves).
Class 92.5 — 10.5–12 lbs/ft³ (e.g. computers, monitors, appliances).
Class 100 — 9–10.5 lbs/ft³ (e.g. boat covers, wine cases, canvas).
Class 110 — 8–9 lbs/ft³ (e.g. cabinets, framed artwork).
Class 125 — 7–8 lbs/ft³ (e.g. small household appliances).
Class 150 — 6–7 lbs/ft³ (e.g. auto sheet-metal parts, bookcases).
Class 175 — 5–6 lbs/ft³ (e.g. clothing, couches, stuffed furniture).
Class 200 — 4–5 lbs/ft³ (e.g. aircraft parts, aluminum tables).
Class 250 — 3–4 lbs/ft³ (e.g. mattresses, plasma TVs, bamboo furniture).
Class 300 — 2–3 lbs/ft³ (e.g. wood cabinets, model boats, tables/chairs setups).
Class 400 — 1–2 lbs/ft³ (e.g. deer antlers, very light bulky goods).
Class 500 — under 1 lb/ft³. The lightest, bulkiest, or most fragile/high-value freight (e.g. ping-pong balls, gold leaf).

Treat the density bands as a guideline, not gospel. The definitive class for any given commodity is whatever its actual NMFC listing says — some items are fixed at a class regardless of density, and some carry released-value or handling caveats. Density is the deciding number only for commodities the NMFC classifies on density.

The four factors: density, stowability, handling, liability

NMFC assigns class using four transportation characteristics. For many commodities density dominates, but the other three can move an item up the scale on their own.

Density. Weight per cubic foot. The single biggest driver for most freight — dense shipments use less trailer space per pound and rate lower.
Stowability. How easily the item loads alongside other freight. Hazardous materials, odd shapes, overlength items, and things that can't be stacked stow poorly and rate higher.
Handling. Whether the shipment needs special care — fragile packaging, non-standard footprint, or equipment to move. More handling, higher class.
Liability. Value per pound, fragility, perishability, and theft or damage risk. High-value or easily-damaged freight carries more carrier liability and rates higher.

How to calculate freight density

Density is the number brokers get asked about most, because it is the one you can compute from the shipment's own dimensions and weight. The formula is straightforward:

Step 1 — volume in cubic feet: (length × width × height in inches) ÷ 1,728. (1,728 is the number of cubic inches in a cubic foot.)
Step 2 — density: weight in pounds ÷ cubic feet.

Worked example: a pallet measuring 48 × 40 × 48 inches is 92,160 cubic inches, which is 92,160 ÷ 1,728 = 53.3 cubic feet. If it weighs 500 lbs, density is 500 ÷ 53.3 ≈ 9.4 lbs/ft³, which falls in the Class 100 band on the density guideline above. Change nothing but the weight — say it's actually 900 lbs — and density jumps to 16.9 lbs/ft³, landing near Class 70 and a materially cheaper rate. That sensitivity is exactly why an unverified weight or dimension is where LTL quotes go wrong.

Why misclassification costs money: reclass fees and disputes

Here is the failure mode every LTL broker knows. A shipment is tendered at, say, Class 70. At the terminal the carrier reweighs and remeasures it, computes a density that actually maps to Class 92.5, reassigns the class, and issues a reclassification adjustment — often alongside a reweigh fee. The original quote no longer holds. Now the broker either eats the difference or goes back to the shipper to explain why the invoice is higher than the number they were quoted.

Reclass and reweigh adjustments are among the most common LTL invoice disputes, and they nearly always trace back to a class, weight, or dimension that was wrong or simply unverified at booking. The fix is not glamorous: get the class and density right — and agreed, in writing — before the freight moves. The commercial version of that discipline is what a good LTL rate quoting workflow is built to enforce.

How Keelway helps LTL brokers with class

Keelway is an AI carrier rep for freight brokers. On LTL freight, the class problem shows up in the inbox: a carrier quotes against one class, the shipper's bill of lading states another, and the coordinator has to notice the gap before booking. That is the specific thing Keelway is built to catch.

It reads the stated class. When a carrier references an NMFC class or dimensions in an emailed quote — or when a shipper BOL states a class — Keelway captures that value and puts it next to the class on your load record.
It surfaces the mismatch. When the two disagree, or when quoted dimensions imply a different density than the class on file, Keelway flags it as an open item for the coordinator, before the booking is confirmed.
It keeps the trail. The class you agree on is part of the email thread and the accepted-carrier record, so if a reclass dispute arises later, the agreed class is in the file rather than lost in the inbox.

The honest limit. Keelway does not assign, invent, or look up freight class, density, or NMFC codes, and it is not a classification authority. It surfaces and flags what the carrier and shipper stated, so a human resolves the class with the NMFC and the commodity's real specs. Assigning class is — and should remain — a human decision. That is the same honest framing we apply across the Keelway LTL product: Keelway makes the discrepancy impossible to miss; it does not pretend to be the classification.

Frequently asked questions

What is NMFC freight class?+

NMFC freight class is a standardized code from the National Motor Freight Classification, published by the National Motor Freight Traffic Association (NMFTA), that groups less-than-truckload (LTL) commodities into 18 classes ranging from 50 to 500. The class summarizes how difficult and costly a commodity is to transport based on four characteristics — density, stowability, handling, and liability — and it is a primary input into the LTL rate a carrier charges. A lower class (like 50) is dense, durable, and cheap to ship; a higher class (like 500) is light, bulky, fragile, or high-value and costs more per pound.

How many freight classes are there?+

There are 18 NMFC freight classes: 50, 55, 60, 65, 70, 77.5, 85, 92.5, 100, 110, 125, 150, 175, 200, 250, 300, 400, and 500. Class 100 sits roughly in the middle. The full range runs from 50 (densest, cheapest to ship) to 500 (lightest or most fragile, most expensive to ship).

What are the four factors that determine freight class?+

NMFC class is set by four transportation characteristics: density (weight per cubic foot), stowability (how easily the item loads alongside other freight — hazmat, odd shapes, and overlength items stow poorly), handling (whether the item needs special care to load, move, or protect), and liability (value per pound, fragility, perishability, and theft or damage risk). For many commodities, density is the dominant driver; for others, the commodity has a fixed NMFC listing that assigns a class regardless of density.

How do you calculate freight density?+

Density is weight divided by volume. First 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). Then divide the shipment weight in pounds by that cubic-foot figure. For example, a pallet 48 × 40 × 48 inches is 92,160 cubic inches ÷ 1,728 = 53.3 cubic feet; at 500 lbs that is 500 ÷ 53.3 ≈ 9.4 lbs per cubic foot, which falls in the Class 100 density band under the common density guideline. Density alone does not always set the class — the item's actual NMFC listing governs — but for density-based items it is the deciding number.

Why does misclassifying freight cost money?+

If a shipment is tendered at a lower class than the commodity actually warrants, the carrier can reweigh and remeasure it at the terminal, reassign it to the correct (higher) class, and issue a reclassification adjustment — an added charge on top of the original quote. The broker is then left explaining to the shipper why the invoice is higher than the quote. Reclassification and reweigh adjustments are one of the most common sources of LTL invoice disputes, and they almost always trace back to a class or density figure that was wrong or unverified at booking.

What is the difference between an NMFC number and a freight class?+

An NMFC item number identifies the specific commodity in the classification (for example, a particular type of machinery or packaged good), while the freight class (50–500) is the transportation rating assigned to that item. Some NMFC items carry a single fixed class; others are 'density-based' and the class depends on the shipment's actual density at the time of shipping. Getting the NMFC item number right is what determines whether class is fixed or must be computed from density.

Does Keelway assign freight class for me?+

No. Keelway does not assign, invent, or look up NMFC codes or freight class, and it does not calculate density on your behalf as an authority. What it does is read the class and dimensions a carrier or shipper states in the emailed quote or bill of lading, compare them against the class on your load record, and surface a flag when they disagree — so a human can resolve the class before booking rather than after a reclass invoice arrives. Assigning class remains a human decision informed by the NMFC and the commodity's actual specs.

LTL · NMFC-aware · AI-native