Understanding NMFC Freight Class
The National Motor Freight Classification (NMFC) system assigns freight classes from 50 to 500 based on four factors: density, stowability, handling requirements, and liability. NMFC Rule 18 allows density-based classification for commodities without a fixed code, which is what this calculator uses. Higher density cargo receives a lower freight class and typically lower shipping rates.
This calculator computes your shipment's density (pounds per cubic foot) and maps it to the 18 standard freight classes used by LTL carriers. Use it to verify carrier quotes, optimize packaging, and understand how box dimensions affect your shipping costs.
How to Use This Tool
Enter Package Dimensions
Input the Length, Width, and Height of your package. Toggle between Imperial (inches) or Metric (mm) units.
Enter Package Weight
Input the actual weight of your shipment. Toggle the pallet weight option to include or exclude standard pallet weight (~45 lbs).
Add Multiple Packages (Optional)
If shipping multiple packages, click "Add Package" to include additional items with different dimensions.
View Your Freight Class
The calculator instantly displays your density, freight class, and shows where you fall on the density gauge.
Understanding Your Inputs
Length × Width × Height
External dimensions of the carton or pallet. Measure the longest points including any overhang or irregular shapes.
Actual Weight
Total weight of the cargo. Remember to include packaging materials like boxes, pallets, and shrink wrap.
Include Pallet Weight
Toggle this on to add ~45 lbs for a standard GMA pallet. Carriers weigh everything on the scale.
Unit System
Switch between Imperial (inches/lbs) and Metric (mm/kg). Values convert automatically when you switch.
Reading Your Results
Density (PCF)
Pounds per cubic foot. Calculated as: Weight ÷ (L × W × H ÷ 1728). Higher density = lower freight class.
Freight Class
NMFC class from 50-500. Class 50 is densest/cheapest; Class 500 is lightest/most expensive.
Density Gauge
Visual indicator showing where your shipment falls on the density spectrum relative to class thresholds.
Total Cubic Feet
Volume of your shipment in cubic feet. LTL carriers use this for space allocation and pricing.
Density Calculation
Automatically calculates density (lbs/ft³) from your package dimensions and weight to determine freight class.
Single & Multi-Package
Calculate for a single package or add multiple packages with individual dimensions and quantities.
Unit Toggle
Switch between Imperial (in/lb) and Metric (mm/kg) units. Values convert automatically.
Pro TipOptimize Your Packaging
Lower density = higher class = higher cost. If your freight class is high, consider using smaller boxes, removing excess packaging, or stacking items on a pallet to increase density. Moving from Class 100 to Class 85 can reduce rates by 10-15%.
Freight Class & NMFC Calculation Data
What is it?
Freight class is a standardized pricing classification used by Less-Than-Truckload (LTL) carriers in the United States, defined by the National Motor Freight Traffic Association (NMFTA). It is determined primarily by the density, stowability, handling, and liability of a product, and is used to establish shipping rates.
The Formula
How to calculate: Total Weight (lbs) ÷ Total Volume (cubic feet)
Industry Benchmarks
Frequently Asked Questions
The National Motor Freight Classification (NMFC) code is a standardized code assigned to every commodity shipped via LTL freight in the US. The code determines the item's freight class. While many items are purely density-based (Rule 18), others have specific NMFC codes that dictate their class regardless of density.
Under NMFC Rule 18, density is the primary driver of freight class for commodities not specifically named. The higher the density (pounds per cubic foot), the lower the freight class. Lower freight classes result in cheaper LTL shipping rates per hundredweight (CWT).
The 'bumping clause' (NMFC Item 171) allows shippers to artificially declare a higher weight on their Bill of Lading to push their shipment's density into a lower freight class, resulting in a lower total shipping cost. This is legal and often saves money on border-line density shipments.