The Short Answer
PCF (Pounds per Cubic Foot) is the "Density Score" of your shipment. We calculate it by dividing Weight by Volume.
The higher the PCF, the lower the Freight Class, and the cheaper the shipping rate.
Example: 50 PCF = Class 50 (Cheap). 3 PCF = Class 300 (Expensive).
The 11 Density Groups
The NMFC (National Motor Freight Classification) groups all freight into 18 classes, but for density-based items, there are 11 brackets you need to memorize.
| Freight Class | PCF Range | Typical Item |
|---|---|---|
| Class 50 | > 50 PCF | Bolts, Steel, Bricks |
| Class 55 | 35 - 50 PCF | Hardwood Flooring |
| Class 60 | 30 - 35 PCF | Car Parts, Tiles |
| Class 65 | 22.5 - 30 PCF | Books in boxes |
| Class 70 | 15 - 22.5 PCF | Auto Parts, Food |
| Class 77.5 | 13.5 - 15 PCF | Tires, Clothing |
| Class 85 | 12 - 13.5 PCF | Crated Machinery |
| Class 92.5 | 10.5 - 12 PCF | Computers, Monitors |
| Class 100 | 9 - 10.5 PCF | Boat Covers, Canvas |
| Class 110 | 8 - 9 PCF | Framed Art (packed) |
| Class 125 | 7 - 8 PCF | Small Appliances |
| Class 150+ | < 7 PCF | Furniture, Kayaks |
The Mechanics: Why Density Rules
LTL carriers sell Trailer Space.
A standard 53-foot trailer has roughly 3,500 cubic feet of space, but can only carry 45,000 lbs legally.
Scenario A (High Density): If you fill the trailer with feathers (Class 500, <1 PCF), the trailer is full (cubed out) but only weighs 3,000 lbs. The carrier burns fuel to move empty air. This is expensive.
Scenario B (High Density): If you fill the trailer with bricks (Class 50, >50 PCF), the trailer hits 45,000 lbs while only being 1/4 full of volume.
The "Sweet Spot" for carriers is around 15-22.5 PCF (Class 70). This density allows them to fill the trailer's volume AND weight capacity simultaneously, maximizing revenue per mile. That is why Class 70 is the "Standard" rate, and everything else is adjusted up or down from there.
2026 Trend: Automated Classification
In the past, you could "fudge" the numbers. You could guess your class.
Today, carriers like XPO, Estes, and FedEx Freight use Dimensioners (Dimensioning Machines). Every pallet is scanned by lasers as it moves off the forklift. The machine calculates L x W x H instantly, measures weight, computes PCF, and assigns the Class automatically.
If your BOL says "Class 70" but the laser says "13.2 PCF" (Class 77.5), the billing software automatically updates the invoice. There is no human involved. The only way to win is to be accurate.
Don't Get Re-Classed
Calculate your exact PCF and find your Class before the carrier does.
Calculate ClassGlossary
Density-Based Class
Determining freight class solely by mathematics (PCF) rather than commodity name.
W&I Certificate
Weight & Inspection document proving the carrier re-weighed your freight.
Cubing Out
Filling a trailer's volume before reaching its weight limit.
NOI (Not Otherwise Indexed)
Catch-all category for items not specifically listed in NMFC, usually density-based.
Frequently Asked Questions
Disclaimer: Determining Freight Class is complex. Always consult the official NMFC 100 series for final authority.