What Is the CBM Unit of Measure?

CBM (cubic meter) is a widely used unit of measure in shipping and logistics to determine the volume of shipments. It is applicable to both domestic and international freight, as well as warehousing and manufacturing. It represents the space occupied by goods and is used across supply chain operations. 

Formula for calculating CBM

The CBM of a shipment is calculated by multiplying its length, width, and height:

CBM (m3) = L * W * H

For example, an item that is 2.5 m in length, 2.0 m in width, and 3.0 m in height would be 15 CBM. To account for items of varying sizes, determine the CBM of each and add them together. For irregular shapes, only consider the longest dimensions.

To calculate the CBM of cylindrical items, use the following formula:

π * Height * Radius² (m3) = CBM

Objective of using CBM in shipping

CBM is primarily used in shipping to make the following critical calculations for all modes of transport: 

Dimensional weight

Dimensional weight is used for ocean shipments where volume is the primary focus. It is calculated as follows:

Dimensional weight (kg) = CBM / Dimensional weight factor

Dimensional weight factor (DIM factor) is the volume of cargo allowed per unit of weight. To simplify and standardize freight pricing, different modes of transport use varying weight standards for 1 CBM.

Chargeable weight

Chargeable weight is used for light shipments that may take a lot of space, critical for air freight. For example, a pallet of inflatable pool toys might take up the same space as a pallet of metal pipes, but the weight difference is substantial. It factors in the calculated dimensional weight and is represented as:

Chargeable weight (kg) = Max(Actual weight, Dimensional weight)

The shipment will be charged based on whichever weight is greater.

Freight class

This system is primarily used in the US to categorize goods transported through Less Than Truckload (LTL) shipping. The freight class is determined by factoring in the CBM and weight of the shipment. For example, a pallet of inflatable pool toys takes up a volume of 1 CBM. Let’s say the total weight is 10 kg. First, we calculate the density, which amounts to 10 kg/m3 or 0.62 lb/ft3. This falls under class 500 i.e., packages under 1 lbs. per cubic feet, reflecting the highest applicable charges. 

Benefits of using CBM

• Accurate costs: CBM measure allows exporters to precisely estimate the cost of shipping based on the volume of the cargo, leading to transparent and fair pricing.

• Simplified documentation: CBM is the standard unit of measure in various shipping documents. It can simplify paperwork and ensure regulatory compliance.

• Space efficiency: Knowing the CBM values of transport goods can improve planning and space utilization within shipping containers, optimizing the number of shipments and promoting cost savings.

• Improved load management: Accurate CBM measurements help plan the layout of cargo, ensuring balanced load distribution.

Applications

The CBM unit of measure finds its applications in the following supply chain processes:

• Shipping: CBM is used in shipping to assess how much space your shipment will take on the cargo, determining transit costs. Accurate CBM calculations enable efficient space utilization in ships, trucks, and aircraft, maximizing cargo capacity.

• Warehousing: It is also an essential metric in warehousing as understanding the CBM of stored goods helps calculate storage costs. It enhances layout planning and enables warehouse managers to optimize inventory levels, mitigating over- and under-stocking risks.

• Manufacturing: In manufacturing, CBM is used to calculate the space required for raw materials, work-in-progress items, and finished goods. This aids in planning the layout of the production floor and ensures efficient handling and movement of materials, improving productivity.