If you ship LTL freight, density is one of the most important numbers you need to understand. Freight density, measured in pounds per cubic foot (PCF), directly determines your freight class, which in turn determines your shipping rate. Getting density right on your bill of lading prevents costly reclassification fees and ensures you are paying the correct rate for your freight.
How to Calculate Freight Density
The formula is simple: Density = Weight (lbs) / Volume (cubic feet). Volume = Length x Width x Height (all in inches) / 1,728. For example, a pallet measuring 48" x 40" x 48" weighing 1,200 lbs has a volume of 53.3 cubic feet and a density of 22.5 PCF. This falls into NMFC class 70 (15.0-22.5 PCF), one of the most common and cost-effective freight classes. If that same pallet only weighed 600 lbs, density drops to 11.3 PCF, pushing it to class 85 (12.0-15.0 PCF), which costs 15-25% more per hundredweight.
The Freight Class-Density Relationship
NMFC freight classes range from 50 (highest density, lowest rate) to 500 (lowest density, highest rate). The relationship is inverse: denser freight costs less to ship because it uses truck space more efficiently. Here is a simplified breakdown: Class 50 requires 50+ PCF, class 55 needs 35-50 PCF, class 60 is 30-35 PCF, class 65 is 22.5-30 PCF, class 70 is 15-22.5 PCF, class 77.5 is 13.5-15 PCF, class 85 is 12-13.5 PCF, and classes 92.5-500 cover densities below 12 PCF. For the full classification system, see our freight class guide.
Why Carriers Reweigh and Reclassify
LTL carriers reweigh and remeasure freight at their terminals. If your declared weight and dimensions do not match, the carrier will reclassify the shipment to the correct class and bill you the difference plus a reclassification fee ($50-$150). In 2026, carriers are using automated dimensioning systems that measure every piece that crosses the dock. Inaccurate bills of lading are caught almost 100% of the time. The solution is simple: measure and weigh accurately before shipping.
Optimizing Density to Lower Costs
Since higher density means lower freight class and lower rates, optimizing density is a direct path to savings. Use right-sized packaging to eliminate void space. Stack products efficiently on pallets to minimize height relative to weight. Use heavier-gauge pallets if they significantly reduce overall height. For products that naturally have low density (pillows, plastic containers, foam products), consider compressed or flat-pack packaging. Even modest density improvements can shift your freight to a lower class, saving 15-25% on that shipment.
Density-Based Pricing Programs
Some LTL carriers offer density-based pricing as an alternative to traditional class-based pricing. Under density pricing, your rate is determined solely by the shipment's density and distance, bypassing the NMFC classification system entirely. This can simplify pricing and benefit shippers whose freight is frequently reclassified. Ask your freight partner whether density-based pricing programs could reduce your costs.