What is freight class?

An NMFC classification number from 50 to 500 that determines your LTL shipping rate. Lower classes (50, 55, 60) are cheaper per hundredweight because the freight is dense, easy to stack, and efficient to transport. Higher classes (300, 400, 500) are more expensive because the freight is light and bulky.

How is freight class determined?

For most commodities, class is determined by density: weight divided by cubic feet. Some commodities have assigned classes regardless of density, based on handling difficulty and liability. This tool uses density for general freight and a lookup table for specific commodities. Add a buffer of 10 to 15% above the calculated figure to account for measurement variation and material waste.

Why do carriers reclassify my freight?

Carriers re-measure and re-weigh shipments at the dock. If your declared dimensions or weight were inaccurate, or if the commodity does not match the class you declared, the carrier issues a freight bill correction. These can add $50-$300 or more to a shipment.

What is the most expensive freight class?

Class 500 applies to items with density below 1 lb per cubic foot: ping pong balls, boat cushions, mattresses, low-density foam. These take up enormous trailer space relative to weight, so carriers charge very high rates per hundredweight.

What does non-stackable mean for freight class?

If your freight cannot be stacked (marked TOP LOAD ONLY), it occupies more of the trailer's effective cube space because nothing can be placed on top of it. Some carriers apply a non-stackable surcharge or reclassify the shipment upward. Always disclose non-stackable status when booking.

Is this tool accurate for final billing?

This tool provides an estimate for quoting purposes based on density. The final class is determined by the carrier at the time of pickup based on their actual measurement. Use this tool to get the right class before requesting quotes and ensure your dimensions and weight are accurate.

Freight Class Calculator (NMFC)

This calculator determines the NMFC freight class for your LTL shipment using either the density method (weight and dimensions) or a commodity type lookup. Enter your shipment weight and dimensions to calculate density and map it to the correct class, or select your commodity type from the pre-loaded lookup table.

100% client-side. Inputs stay in your browser (ons-freight-class-inputs).

Final class is determined by the carrier at pickup. This estimate is for quoting purposes.

Weight (lbs)

Length (in)Width (in)Height (in)

Stackable

Freight class

100

Density

9.38 lb/cu ft

Volume

53.33 cu ft

Mid-density freight. Typical for cartoned goods. Rates sit in the middle of the NMFC scale.

Mid-range CWT

500 lbs on 48×40×48 in

NMFC density class table

Your estimated class row is highlighted when using the density method.

Class	Density (lb/cu ft)
50	50 or more
55	35 to under 50
60	30 to under 35
65	22.5 to under 30
70	15 to under 22.5
77.5	13.5 to under 15
85	12 to under 13.5
92.5	10.5 to under 12
100	9 to under 10.5
110	8 to under 9
125	7 to under 8
150	6 to under 7
175	5 to under 6
200	4 to under 5
250	3 to under 4
300	2 to under 3
400	1 to under 2
500	under 1

How this tool works

The freight class calculator determines the NMFC (National Motor Freight Classification) class for LTL shipments, which carriers use to calculate freight rates. The NMFC system assigns class numbers from 50 (dense, low-cost) to 500 (light, fragile, high-cost) based on four characteristics: density, stowability, handling requirements, and liability. Density is the primary driver for most commodities: density = weight (lbs) / volume (cu ft), where volume = (length x width x height in inches) / 1,728. Class 50 covers freight above 50 lbs/cu ft; Class 500 covers freight below 1 lb/cu ft. The tool computes density from entered dimensions and weight, cross-references the appropriate NMFC commodity category, and returns the class. It also shows the resulting freight rate multiplier versus Class 100 (the baseline). Key assumption: the NMFC class is a starting reference; actual carrier rates apply a base rate per hundredweight multiplied by a class factor plus accessorial charges. Discounts negotiated directly with carriers are not reflected in the tool. Edge case: freight that is palletized is measured to the pallet footprint, not the product carton dimensions. A 20 lb box on a standard 48x40 pallet occupies a much larger cubic volume than the carton alone, substantially lowering density and raising the class -- always enter pallet dimensions when the shipment will move on a pallet.

Worked example

A pallet of machine parts: 500 lbs, dimensions 48 x 40 x 48 inches. Volume: (48 x 40 x 48) / 1728 = 53.3 cubic feet. Density: 500 / 53.3 = 9.38 lbs/cubic foot. The 9-10.5 range maps to Class 100. A second example: lightweight foam packaging, 50 lbs, 60 x 40 x 40 inches. Volume: 55.6 cubic feet. Density: 0.90 lbs/cubic foot. Below 1: Class 500 (most expensive). Dense, heavy shipments get cheap Class 50. Light, bulky shipments get expensive Class 500.

Frequently asked questions

What is freight class?
An NMFC classification number from 50 to 500 that determines your LTL shipping rate. Lower classes (50, 55, 60) are cheaper per hundredweight because the freight is dense, easy to stack, and efficient to transport. Higher classes (300, 400, 500) are more expensive because the freight is light and bulky.
How is freight class determined?
For most commodities, class is determined by density: weight divided by cubic feet. Some commodities have assigned classes regardless of density, based on handling difficulty and liability. This tool uses density for general freight and a lookup table for specific commodities. Add a buffer of 10 to 15% above the calculated figure to account for measurement variation and material waste.
Why do carriers reclassify my freight?
Carriers re-measure and re-weigh shipments at the dock. If your declared dimensions or weight were inaccurate, or if the commodity does not match the class you declared, the carrier issues a freight bill correction. These can add $50-$300 or more to a shipment.
What is the most expensive freight class?
Class 500 applies to items with density below 1 lb per cubic foot: ping pong balls, boat cushions, mattresses, low-density foam. These take up enormous trailer space relative to weight, so carriers charge very high rates per hundredweight.
What does non-stackable mean for freight class?
If your freight cannot be stacked (marked TOP LOAD ONLY), it occupies more of the trailer's effective cube space because nothing can be placed on top of it. Some carriers apply a non-stackable surcharge or reclassify the shipment upward. Always disclose non-stackable status when booking.
Is this tool accurate for final billing?
This tool provides an estimate for quoting purposes based on density. The final class is determined by the carrier at the time of pickup based on their actual measurement. Use this tool to get the right class before requesting quotes and ensure your dimensions and weight are accurate.

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