Freight Class Calculator
Enter your cargo dimensions and weight to instantly calculate NMFC freight class and density — no guessing, no surprises on your LTL bill.
Your Freight Class
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Enter dimensions and weight above
What Is Freight Class — and Why Does It Control Your LTL Rate?
Freight class is a standardized number assigned to every LTL shipment by the National Motor Freight Traffic Association (NMFA). It runs from Class 50 (the cheapest) to Class 500 (the most expensive). Carriers use the class to set the base rate for your shipment — higher class means a higher rate per hundredweight (CWT).
The class is determined by four factors, but density is the primary one for most freight. Density is your shipment's weight divided by its volume in cubic feet. Dense cargo (bricks, metal parts) earns a low class and a low rate. Light, bulky cargo (pillows, empty boxes) gets a high class and a high rate — because it takes up trailer space without contributing much weight, which costs the carrier money.
The four NMFC factors
Density
Weight ÷ volume in cubic feet. The primary driver for most commodities. Denser = lower class = lower rate.
Stowability
Can it stack? Is it hazmat? Oddly shaped freight that wastes trailer space gets a higher class.
Handling
Fragile, hazardous, or awkward loads require extra handling — which raises the class.
Liability
High-value or theft-prone goods carry more carrier risk, which can push the class up.
How to calculate density
1,728 converts cubic inches to cubic feet (12³ = 1,728). Always measure the longest point of the shipment including pallet and any overhang — carriers measure the same way when they re-class at the dock.
What happens if your class is wrong?
Carriers re-weigh and re-measure shipments at the dock. If their measurement produces a different class than what you declared, they issue a freight bill correction — you pay the difference plus a re-classification fee, which can add 30–50% to the original quote. Getting the class right before pickup is always cheaper than correcting it after.
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Frequently Asked Questions
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