How do you calculate CBM and Freight Tons in maritime?

Exploring the Calculation of CBM and freight tons in maritime Shipping

The maritime industry and port authorities manage cargo transportation through sea routes. The shipping rates are decided by evaluating various factors, among which the freight ton of the cargo plays a significant role. A freight ton is a unit for measuring the shipment volume to be loaded on transportation modes. Maritime vessels are charged based on the cargo’s weight or volume. Cubic metre or CBM is the measuring unit that determines the space a shipment will occupy in the shipping container. It is beneficial for oversized cargo or shipping containers to be loaded onto the vessel. Let us learn more about calculating the CBM and freight tons in maritime to improve operational efficiency, stowage planning and determining shipping rates. 

What Is CBM? 

CBM, also known as cubic metres, is a unit of measurement for volume widely used in shipping and logistics to measure cargo volume. The volume derived by calculating the CBM is equal to the volume of a cube with sides one metre long, i.e., a cubic metre can be defined as the volume of a cube with each side precisely one metre in length. A cubic metre is a measurement unit used to quantify the volume of a three-dimensional (3D) space. For example – a container, room, or any other object or space is measured in terms of CBM. The unit of measurement has its application in various industries, such as shipping, construction, and logistics, to measure and calculate the volume of objects.  

What is a freight ton? 

A freight ton, also popularly known as a shipping ton or measurement ton, is a unit measuring volume used for shipments such as freight when loaded onto large vehicles, trains, or ships. It does not measure weight but instead measures cargo volume because it is easier to measure the volume of cargo than its weight. Freight ton is used in the calculation of shipping costs. In the shipping and transportation industry, the measurement unit quantifies the weight or volume of cargo transported via roads, rails, air or sea. Regarding a freight ton as a unit of weight instead of volume, 1 freight ton translates to 1,000 kilograms, equivalent to 2,000 pounds. When the freight ton is expressed in ‘volume’, 1 freight ton equals one cubic metre or 1,000 litres of cargo space. Depending on whichever metric results in a higher charge, shipping companies decide between charging based on weight or volume to ensure fair compensation for the transportation of goods. 

Relation between CBM and freight tons in maritime 

CBM and freight ton are units of measurement used in shipping and transportation that help calculate different aspects of goods. Freight tons are used to measure the weight of the cargo, and CBM is used to measure the volume of goods. Both units of measurement are used by shipping companies or carriers to calculate shipping rates, make stowage plans, utilise the storage space and calculate applicable taxes and duties. It depends on the shipping company whether the shipping rates will be charged based on the weight or volume. This is because sometimes the goods are more in volume than in weight, and to have a fair calculation of space and rates, it is essential to consider the relevant unit. 

What is the use of CBM and freight tons in maritime? 

  1. Calculating shipping rates– Freight ton is used in the logistics and transportation industry by various shipping service providers such as shipping companies and ocean carriers to determine the shipping cost. It is based on the weight of the cargo (in kgs or pounds) or shipment volume (expressed as CBM). 
  2. Utilising storage space– Cargo is loaded onto shipping containers, which are then towed onto the designated means of transport. The freight ton needs to be calculated for the optimised cargo accommodation in shipping containers so that no space is wasted. 
  3. Stowage planning– Shipping containers are towed onto ships, trucks or rails. Depending upon the storage space of the transport, knowing the freight ton helps transport authorities build a proper plan based on the standard limit for loading. It helps easily allocate resources such as power backups or specialised equipment when dealing with various cargo types and sizes. 
  4. Calculating duties and taxes– When dealing with cross-border trade, freight ton measurement is used to calculate import and export duties, taxes, and tariffs, which are often based on the value or volume of the cargo. 

How do you calculate CBM and freight tons in maritime? 

Shipping companies, shippers and 3PL and 4PL logistics service providers calculate CBM and freight ton to quantify the cargo space, formulate stowage plans, and calculate the shipping rates. When calculating cubic metres, the authority in charge must measure the length, width, and height of the cargo in metres, followed by multiplying the resulting value. 

CBM (cubic metre) = Length (in metres) × Width (in metres) × Height (in metres) 

When measuring freight tons where the weight is specified, you need to focus on the unit of measurement. 

If the weight is in pounds, then, 

Freight tons = weight in pounds/2,000 

If the weight specified is kilograms, then, 

Freight tons = weight in kilograms/1,000

How does CBM affect freight rates? 

  1. Change in pricing– Some shipping companies and ocean carriers use volume-based pricing instead of pricing based on cargo weight. CBM is the standard basis for calculating freight rates in such cases. This type of pricing is prevalent for lightweight but bulky cargo. In such cases, higher CBM equals higher freight rates, where you pay for the space your shipment occupies. 
  2. Cargo consolidation– CBM pricing becomes futile here if you are exporting a shipment where the cargo of different sizes is being loaded for shipment. In this case, the overall freight rate may be influenced by the highest CBM item. Freight pricing may increase as large items take up a significant volume. 
  3. Cargo density– Low-density cargo takes up a lot of space relative to its weight. In such cases, you may be charged based on CBM because the weight does not reflect the amount of space the cargo will take. Conversely, cargo weight-based shipping rates are suited for calculating the price of dense cargo. 
  4. Oversized cargo– The CBM threshold increases for oversized freight. Loading and unloading of such goods are also taxed as additional charges by the authorities, such as terminal handling charges or inland haulage charges. 

This is how shipping companies calculate CBM and freight tons in maritime to impose rightful shipping rates and improve their stowage planning to utilise space and generate revenue.

 LOTUS Containers is a leading marketer of shipping container solutions and aims to offer all types of shipping containers, including 53 ft intermodal containers, reefer containers, and double-door containers, among many other types for maritime shipping.

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