What is Freight Class?
In the Less-Than-Truckload (LTL) shipping industry, freight class is a standardized pricing classification established by the National Motor Freight Traffic Association (NMFTA). It determines how much you pay to ship your goods. Classes range from 50 (the cheapest, highest density) to 400 (the most expensive, lowest density). By correctly identifying your freight class using a density calculator, you ensure accurate quotes and avoid unexpected carrier re-classification fees.
How to Calculate Freight Density — Step-by-Step
Calculating freight density involves simple math, but accuracy is critical. Here is the formula:
- Measure the Dimensions: Measure the Length, Width, and Height of your shipment in inches. Always include the pallet dimensions if the shipment is palletized.
- Calculate Volume in Cubic Inches: Multiply Length × Width × Height.
- Convert to Cubic Feet: Divide the cubic inches by 1,728 (the number of cubic inches in a cubic foot).
- Calculate Density (PCF): Divide the total weight of the shipment (in pounds) by the total volume (in cubic feet).
The resulting number is your Pounds per Cubic Foot (PCF), which maps perfectly to the 13-tier NMFC density guidelines.
NMFC Codes vs Density-Based Classification
There are two primary ways freight is classified: by a specific NMFC Item Code assigned to particular commodities (like auto parts, plastics, or textiles) based on four transportability factors (density, handling, stowability, liability), and by pure Density. Today, an increasing number of carriers and commodities use purely density-based classification because it is objective and easily verifiable via dimensional scanners at cross-dock terminals.
Freight Class Chart with Examples
| Class | Density (PCF) | Typical Commodities |
|---|---|---|
| Class 50 | 50+ | Nuts, bolts, steel, heavy building materials |
| Class 85 | 12 to 15 | Auto parts, cast iron stoves, boxed machinery |
| Class 150 | 6 to 8 | Assembled wooden furniture, sheet metal parts |
| Class 400 | Less than 1 | Ping pong balls, highly fragile/bulky items |
How to Avoid Re-Classification Fees
Carriers frequently re-weigh and re-measure pallets at terminals. If your Bill of Lading (BOL) lists an incorrect class (e.g., you guessed Class 70 but the true density dictates Class 100), the carrier will issue a "Re-Class Fee" adjustment on your final invoice. The best way to protect your profit margins is to document dimensions accurately, always factor in the pallet weight and size, and use an accurate density calculator before quoting shipping rates to your customers.