Module 2 of 7 · 12 min

Describing freight correctly

Class, NMFC, density and dimensions — what they mean, how carriers verify them, and why a wrong description is the most common way a broker loses money.

By the end you will be able to

Calculate density and convert it to a freight class
Explain the difference between class and NMFC
Recognise the descriptions most likely to trigger a reweigh or reclass

Class is a proxy for cost to haul

Freight class runs from 50 to 500. Low class is cheap to move, high class is expensive. It is set by four characteristics: density, stowability, handling and liability.

For most everyday commodities, density does the work. Something heavy and compact fills a trailer's weight limit before its space limit, so the carrier gets paid well for the room it takes — class 50 or 55. Something light and bulky fills the space long before the weight, so it earns the carrier very little per foot — class 250, 300, higher.

Stowability, handling and liability adjust it. Freight that cannot be stacked, that needs special equipment, or that is attractive to thieves prices higher than its density alone suggests.

How to work out density

Density is pounds per cubic foot. Multiply length × width × height in inches, divide by 1,728 to get cubic feet, then divide the weight by that.

Measure the whole handling unit, not the product. A pallet is 48 × 40 and adds about 5 inches of height, and if anything overhangs the pallet edge, the overhang counts.

Density (lb/ft³)	Typical class
50 and over	50
35 – 50	55
30 – 35	60
22.5 – 30	65
15 – 22.5	70
13.5 – 15	85
12 – 13.5	92.5
10.5 – 12	100
9 – 10.5	110
8 – 9	125
6 – 8	150
4 – 6	175
2 – 4	250
1 – 2	300
Under 1	400+

Density to class — the common bands

Class is not NMFC

The NMFC is the classification directory: an item number identifying a specific commodity, which then tells you its class. Some NMFC items have a fixed class regardless of density; others are density-based, meaning you must calculate.

Brokers routinely quote a class with no NMFC. That works until the carrier inspects the freight and applies the NMFC item they think fits, which may carry a different class. Supplying the NMFC number is how you make the description defensible.

How carriers check, and what it costs when they do

Most LTL carriers run freight through automated dimensioners at the terminal — a scanner that measures and weighs every handling unit in seconds and photographs it. The days of a wrong description going unnoticed are gone.

When the measurement disagrees with the BOL you get a reweigh or a reclass, and a corrected invoice arriving days or weeks later. By then you have very likely already invoiced your customer at the old number.

That gap is where broker margin dies. It is rarely one catastrophic error; it is a steady drip of $80 and $150 corrections on shipments you thought were profitable.

Worth remembering

Density drives class for most commodities — measure the handling unit, not the product
Overhang counts, and pallets add about 5 inches
Class and NMFC are different things; supplying the NMFC makes your quote defensible
Carriers dimension automatically now — a wrong description will be found
Corrections usually arrive after you have invoiced, so they come out of margin

Check yourself

3 questions. You will see why each answer is what it is.

1Two pallets, each 48 × 40 × 48 in, 900 lb total. What is the density?

2What is the difference between freight class and an NMFC number?

3You quoted class 70. The carrier's dimensioner puts it at class 125 and reissues the invoice. You have already billed your customer. What has happened to that shipment?