Formula
Inches become cubic feet, then the weight is divided by that volume:
density = weight / (length × width × height / 1728)
1,728 cubic inches are one cubic foot. A freight class is not assigned. The cost page prices a hundredweight you already know.
Assumptions
- Dimensions are the shipped handling unit, in inches.
- Weight is pounds of that same unit.
- Density is the average over the whole cube, including air in the box.
Worked example
A 40 by 48 by 36 inch unit weighing 500 pounds has a density of 12.5 lb/ft³.
Input definitions
- Density
- Pounds per cubic foot of the handling unit.
Limitations
NMFC class also depends on the commodity, stowability, and handling. Density alone does not set the class or the rate.
Questions
Why is the example 12.5?
The box is 40 cubic feet. Five hundred pounds divided by 40 is 12.5 pounds per cubic foot.
Does this pick a freight class?
No. It stops at density so the class rules are not guessed.