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Freight Class 101

In less-than-truckload (LTL) freight shipping, knowing the freight class of your shipment is a crucial element in accurately determining the cost of a shipment.

Freight classes – the numerical categorizations of a shipment’s durability in transit, range from Class 50 to Class 500. Generally speaking, the lower number freight class that is assigned to your shipment, the less it will cost to move.

How to determine a freight class

Shippers and freight forwarders use a couple of different approaches when they work to determine an item’s freight class.

Density-based freight class

The easiest way to quickly identify an item’s freight class is by calculating the freight’s density. To do this, you need to know the item’s dimensions and weight. With this information, you can use these two simple formulas to calculate the freight’s density.

First, calculate the item’s total Cubic inches by multiplying its length, width and height in inches.

L x W x H = Cubic Inches

Then, divide the total Cubic Inches by 1,728. In this calculation to determine Cubic Footage, 1,728 is a static number that never changes.

Cubic Inches / 1,728 = Cubic Footage

Finally, calculate the density by dividing the item’s total weight in pounds by its Cubic Footage.

Total Weight / Cubic Footage = Density
(expressed as pounds per cubic foot)


Let’s say we have a pallet of freight that weighs 1,250 lbs. and has the following dimensions: 48 inch length x 48 inch width x 50 inch height.

  1. 48 x 48 x 50 = 115,200 Cubic Inches
  2. 115,200 / 1,728 = 66.67 Cubic Footage
  3. 1,250 / 66.67 = 18.75 pounds per cubic foot = Density

Now that you have calculated the density of the freight, you can use that value to determine the freight class by referencing a Full Range Density Chart. This lists the breakdown of freight classes based on an item’s density, or pounds per cubic foot.



Minimum Average Density (in pounds per cubic foot)
30 60
22.5 65
15 70
12 85
10 92.5
8 100
6 125
4 175
2 250
1 300
Less than 1 400

In the example, the density of the shipment was 18.75 pounds per cubic foot. Referencing the chart, we can see this assigns a Class 70 to the shipment.

For those who prefer not to do manual calculations, there are freight class calculators available online that can assist in determining freight class using the dimensions and weight.


  • Do not guess or estimate weight or dimensions! Carriers could measure and weigh your freight using certified equipment. If they determine a reclassification is necessary, it could trigger additional fees or delays.
  • When determining a shipment’s weight, be sure to include the pallet, crate and all packing material.
  • Carriers that use NMFC numbers as their standard may reclassify shipments with assigned density-based freight classes.
  • Density freight classes are based on the freights’ ship-ability. An item taking up more space and weighing less will often be more fragile than an item taking up less space, but weighing more. The later will be denser, and likely will have a lower freight class number – hence cheaper to ship.



NFMC classifications to determine freight class

In the freight industry, using a National Motor Freight Classification number is a way to ensure your freight class will not get reclassified by the carrier. NFMC numbers clearly define certain products and items to indicate their freight class.

In general, it NMFC numbers classify products based on how fragile or durable they are to determine the freight class. There are three types of NMFC numbers: full range density-based, partial density-based, and item-specific.


1. Full Range Density-Based

A Full Range Density NMFC, such as 49880 (see below), works off of the density chart previously used to determine the density of an item. These are the most common types of NMFCs that carriers rely on to properly classify freight that is transported on their trailers. This is likely because it takes less searching for them!

2. Partial Density-Based

A Partial Density-Based NMFC, such as 133300 which covers machinery and machine parts, takes density into account when determining the classification. However, while still based on upon pounds per cubic foot, these NMFCs are not as strict.

The item must still be accurately identified, but the density range used for classification is a bit broader. Partial density-based NMFCs allow items that would normally be classed, for example, at 100 to be shipped at 92.5. Items that would normally ship at Class 85 could be shipped at Class 60. These small adjustments can often save shippers a great deal of money.

3. Item-Specific

Item-specific NMFCs are not density-based but based on strict product guidelines. A good example of an item-specific NMFC is 19940. This NMFC is Class 85 but in order to use this NMFC, the product must meet strict guidelines. The wording of the NMFC states, “Transmissions or Clutches; or Parts thereof, in boxes or crates.”

If you are shipping this exact item and it meets all of the criteria then using this NMFC should not be a problem. However, if it fails to meet even one of the stated criteria, it is likely the carrier will reclassify the item based on a Full Range Density or Partial Density NMFC relating to this product, resulting in a price increase.

In summary, when determining your freight class using the Density-Based classification do not guess or estimate the weight or dimensions. As you weigh your shipment, include the pallet, crate, and all packing material. If instead you choose to use the NFMC classifications, you have three types of NMFC numbers: full range density-based, partial density-based, and item-specific. These three classifications will prevent reclassification fees and make finding the cost of your shipment easier.

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