What is CBM & How do you calculate it

Measurement of cargo is an important stat to capture in the shipping process. The volume and weight of the cargo are imperative for pricing decisions. Often it may also affect your choice of carrier, mode of storage and loading or unloading. CBM is one measure which is commonly used across the world to denote the volume of the cargo.

What is CBM?

A cubic meter, or CBM, is a unit of measurement for the volume of a shipment. It determines how much space your cargo will take up on a ship, plane, or truck, and thus how much it will cost to transport.

How is CBM calculated?

CBM = length x width x height

This is the CBM cargo volume calculation formula (m3).

Assume you have a 2-meter long, 2 meters wide, and 2-meter-high carton. The volume is then 2 x 2 x 2 = 8 m3.

If you have 10 identical cartons in a single consignment, simply multiply the CBM by the total number of cartons to get the total volume – 8 x 10 = 80 m3.

If the cartons are not the same size, calculate the CBM for each carton separately and add the total.

Difference Between Volumetric Weight & Chargeable Weight

Volume (CBM) is one method of calculating freight in shipping. The other factor is weight. Traditionally, a shipment’s weight is said to determine its transportation cost. Some products like Styrofoam, cotton bale etc. have huge bulk volume but very little proportionate weight.

A shipment of this size would require more space than, say, a shipment of small steel items. However, if freight is charged based on its lightweight, the amount would be nominal. This is where dimensional or volumetric weight and chargeable weight come into play.

Gross Weight: The total weight of your cargo, including packaging, cushioning, and pallets.

Dimensional/Volumetric Weight: Dimensional weight or volumetric weight refers to the volume of cargo converted into its weight equivalent (CBM to kg). You can use the following formula to calculate dimensional weight for the freight mode (air, sea, or road) and carrier:

Dimensional Weight = CBM x DIM Factor Length (cm) x Width (cm) x Height (cm) x Quantity / DIM Factor

The number of packages that comprise a single cargo consignment is referred to as quantity.

The DIM factor, also known as the dimensional weight factor, varies depending on the freight mode (sea, air, courier, or truck) and carrier. The following are commonly used DIM factors:

1 m3 = 1,000 kg or 1 ton of sea freight

1:6,000 for air freight (1 m3 = 6,000 kg or 6 tons). However, if we use the first formula (CBM x DIM Factor = Dimensional Weight), the DIM factor is 1:167, with 1 m3 equaling 167 kg.

1:5,000 courier/express freight (1 m3 = 5,000 kg or 5 tons)

LTL (less than truckload) – 1:3,000 (1 m3 = 3,000 kg or 3 tons).

Chargeable weight: Once you’ve determined your gross weight and dimensional weight, your freight service provider will charge you based on the greater of the two. This is known as chargeable weight. If the gross weight exceeds the dimensional weight, you will be charged based on the former. However, if the dimensional weight is greater, that is the chargeable weight.

How to Use CBM to Calculate Freight?

1. For less-than-container-load (LCL) ocean freight

Assume you are shipping a shipment by the sea that is less than a container load (LCL). (LCL shipping is a method of transporting small amounts of cargo in a shared container.) Shipping lines typically charge freight based on CBM for LCL shipments that weigh less than one ton (1,000 kg). If the cargo weighs more than a ton, freight is calculated based on weight.

2. For Air Cargo

To calculate dimensional weight, we used the second formula to arrive at freight cost:

Length (cm) x Width (cm) x Height (cm) / DIM Factor – and a DIM factor of 1:6000

3. For Road Freight (Truck LTL)

This calculation is based on the dimensional weight formula

Length (cm) x Width (cm) x Height (cm) / DIM Factor, with a DIM factor of 1:3000.

How Does CBM Work for Irregularly Shaped Packages?

So far, all the dimensions and calculations in this article have been for packages with a regular shape, such as a cube or cuboid. A carton is a regular-shaped package for which the formula is Length x Width x Height = CBM. But what if your package is a strange shape? How do you calculate its CBM?

1. A cylindrical package, such as a rolled carpet or a pipe. Measure the height and radius of the package while it is upright (which is half of its diameter). Metric measurements should be taken. Apply the formula

π.r.2 x h = CBM now.

π is the symbol for pi, which is the circumference to diameter ratio of a circle, which is traditionally equal to 3.

The radius is 14 r, and the height is h. (which is equal to the length)

2. Irregularly shaped package: To calculate the CBM of such a package, take its longest length, width, and height. Then multiply the length (max) by the width (max) by the height (max) to get the CBM.

Conversions and Measurements

Because CBM is measured in metres, here’s how to convert your cargo measurements to metres:

• Foot to Meters: Because one foot equals 0.3048 metres, multiply the foot value by 0.3048.
• From Inch to Metre: Because one inch equals 0.0254 metres, multiply by 0.0254
• Centimeter to Meter: Because 1 centimeter equals 0.01 metres, multiply by 0.01

What effect does CBM have on freight rates?

When we say that cargo volume, or CBM, determines your freight cost, we don’t just mean the carrier’s fees for transporting your goods. When you receive a freight quote, it will include several other charges and surcharges, all or some of which may be calculated using CBM. These are some examples:

Terminal service fees: These are the costs associated with the use of terminals’ equipment and property at origin and destination, as well as the use of labor provided by them for cargo loading/unloading and transportation.

Inland haulage charges are the costs of transporting cargo from an inland container depot/container freight station to a port of loading or vice versa.

• Bunker Adjustment Factor (BAF): Also known as Fuel Adjustment Factor, this is an extra charge levied by carriers to account for fluctuations in fuel prices.
• Currency Adjustment Factor (CAF): A surcharge levied by carriers to compensate for fluctuations in currency rates relative to the base exchange rate.

References:

https://www.freightos.com/freight-resources/cubic-meter-calculator-cbm-shipping-free/
https://bowagateglobal.com/2021/04/15/how-to-calculate-cbm/