Commercial trucks haul about 70% of the domestic goods, including manufactured and retail goods, moved in the United States. In 2017, that equaled almost 11 billion tons of freight. To move that much freight, companies and truckers must load their materials as efficiently as possible. In the freight industry, calculating case cubes provides a tool for planning truck loading.
Cube Dimensions Formula
Mathematically, calculating volume using the cube dimensions formula uses the standard formula of length times width times height, or LxWxH. Since all sides of a cube have the same length, the calculation for cubes becomes length cubed, or L3. If the length of the cube is 2 centimeters, for example, then the volume calculation becomes 23, or 2x2x2=8 cm3.
Case Cube Dimensions
The term "case cubes" refers to pallet loads. Pallets, also called skids, can be custom-made, but the two relatively standard size pallets in the U.S. are 42 inches by 48 inches (42"x48") and 48 inches by 48 inches (48"x48"). Certain industries more typically use 40 square inch and 42 square inch pallets. In Europe, the standard sized pallet measures 48 inches by 42 inches (48"x42").
The height of pallets varies from 3.5 inches to 6 inches tall, but the standard pallet is 5.5 inches tall. When loading pallets into a truck, the loader needs to add the height of the pallet to the height of the pallet load.
The height of the load on the pallet is limited by the load capacity of the pallet and the height of the trailer box. Most pallets can hold up to 2,500 pounds, but pallets can be reinforced to carry up to about 4,500 pounds. While the height of the trailer box varies, the height of the door space limits the height of the pallet stack. Door heights on 28-foot trucks (also called "pups") usually are 104 inches while door heights on longer trailers usually are about 105 inches.
Measuring Case Cube Dimensions
When calculating case cube dimensions, first measure the longest part of the load on each pallet. Ideally the length and width dimensions of the load will equal the dimensions of the pallet but shipped materials might not fit with the outside dimensions of the pallet. So, if the materials on the pallet extend beyond the pallet edges, measure the longest dimension in each horizontal direction and the highest point on the pallet.
Case Cube Calculation of Volume
Multiply the length, width and height together to find the total volume of the pallet. For example, if the pallet load matches the dimensions of a 42x48-inch pallet and the pallet load stands 60 inches tall, then the volume of the pallet will be 42 inches times 48 inches times 60 inches (42x48x60), a volume of 120,960 cubic inches. Divide by 1,728 (one cubic foot equals 12x12x12 cubic inches, which is equal to 1,728) to find the volume in cubic feet. Completing the cube calculation shows the volume of this case cube equals 70 cubic feet (ft3).
On the other hand, if the pallet load exceeded the pallet size, the longest measurement in each direction would be used to find the volume. If the load occupied a 42x48-inch pallet but measured 44 inches by 56 inches with a measured height of 60 inches, the volume of the case cube equals 44x56x60 or 147,840 cubic inches. Dividing 147,840 by 1,728 yields a volume of 85.55 ft3.
Loading the Freight Box
A standard 53-foot trailer has a volume of about 4,050 cubic feet. Case cube freight loading may require "turning the skids" to efficiently fit the trailer box. Turning the skids means turning the pallets sideways so they fit better across the width of the trailer box. About 30 42x48-inch pallets can fit in a standard 53-foot trailer, if they are turned.
About 26 48x48-inch pallets will fit into the same trailer. About 24 48x48-inch pallets or 26 42x48-inch pallets, when turned, will fit in a 48-foot trailer.
Pallet Cubic Feet Calculator
On-line pallet cubic feet calculators can be used to calculate the volume of the proposed load. The shipper enters the size of the individual items and the number of those items to be shipped. If the proposed load will include items of different dimensions, these items can be added until the total load volume is calculated. The calculator gives the total volume of the prospective load. (See Resources)
The case cube volume is one factor in shipping freight. The other case cube consideration is weight. Federal regulations limit the total weight of the truck, trailer and load to 80,000 pounds unless a special permit is granted. In general, this limits the load to a maximum of 45,000 pounds. (See Resources)