How to calculate VGM in shipping?

Process of calculating VGM in shipping compliance with a container on a weighbridge

Verified gross mass in shipping refers to the tare weight of the shipping container along with its cargo content. VGM in shipping allows shipping companies to measure the container weight accurately and make container handling and stowage plans accordingly. Shippers have to declare the correct weight of the shipping container to ship their goods to various countries internationally. Shipping companies ask for container weight for various purposes, such as drafting a container stowage plan and scheduling container handling resources at the shipping port. Let us learn more about VGM in shipping. 

About shipping container weight 

The container structure for cargo containers varies based on their size and type. Shipping containers are built based on ISO standards and manufactured to be quickly shipped through various modes of transport- trucks, trains, planes and ships. For this intermodal transportation of shipping containers, the twist locks and corner castings provide strength while handling the containers using cranes and forklifts. Locking rods are attached to the container to seal shipping containers before international transit. All these elements contribute to the weight of the shipping container. Let us learn more about the types of container weights. 

  1. Tare weight– The weight of an empty shipping container, when taken exclusively without any cargo loaded in it, is known as tare weight. 
  2. Net weight– Also known as payload, the net weight defines the weight of cargo that a shipping container can hold without overstuffing it. The payload weight can be calculated by subtracting the container’s tare weight and gross weight. 
  3. Gross weight– When the weight of a container is calculated by adding the container weight and its maximum payload, it is defined as gross weight. 

All this information is painted on the CSC (Convention for Safe Containers) plate on the container door in a shipping container to give shippers and shipping companies a clear picture. 

Factors that contribute to the weight of shipping containers 

The weight of the shipping container depends on various factors- 

  1. Type of shipping containers– Different shipping containers have different internal structures. Insulated and reefer containers have insulation layers or reflective sheets to maintain the container’s internal temperature, which increases the weight of containers. 
  2. Size of shipping container– Different shipping container types are available in the container market, ranging from 10ft, 20ft, 40ft, 45ft, to 53ft intermodal containers. Larger container sizes account for higher tare weight and greater payload than smaller containers.  
  3. Material of shipping containers– Most shipping containers are built of corten steel as they are robust and resistant to corrosion. Although aluminium can also be used for building containers because of its lightweight nature, it does not have the same properties as corten steel. 
  4. Structure of the shipping container– Shipping containers are stacked one on top of another for transporting them across borders. For this, beams and corners are attached to ease container handling. These structures add to the tare weight of the container. 

Importance of container weight in shipping 

The global supply chain works on importing and exporting goods from one country to another using various modes of transport such as road, rail, air, and sea. The goods for transportation are loaded onto standard or high cube containers depending on the cargo requirement. Built from corrugated steel, all cargo containers have a significant weight. Shipping companies need to have specifications of container weight for various reasons- 

  • It helps calculate the ship’s payload to avoid overstuffing containers with cargo, which can lead to cargo damage and accidents during container handling. 
  • The calculation of shipping rates is based on the weight of the cargo container and the cargo in it. 
  • It becomes easier to arrange appropriate container handling equipment if the shipping company knows its weight. 
  • Container stowage plans are based on the container weight to avoid placing heavy-loaded cargo containers on the top as they can fall off the ship during turbulence at sea. 
  • Cargo insurances require shippers to declare the correct container specification, such as container weight with cargo packed. 

What is VGM in shipping? 

VGM in shipping is an acronym for verified gross mass used for calculating the tare weight of the shipping container and its cargo. As a step towards maritime safety of the crew and ship, the International Maritime Organisation (IMO) introduced an amendment to the SOLAS (safety of life at sea) convention in 2016. Under this regulation, the shipper must provide specifications about the verified gross mass of the shipping container. The VGM includes the mass of the shipping container along with its cargo, dunnage, packing material, pallets, and bracing material inside the shipping container. Before loading the container onto ships, shippers must provide the VGM in documented form, potentially through a bill of lading. 

What is the purpose of VGM in shipping? 

Ocean carriers and terminal representatives need to know the verified gross mass of shipping containers for the following reasons- 

  • Shipping companies can create appropriate vessel stowage planning by knowing the accurate weight of shipping containers. Lighter containers are stacked on top of heavier containers for stability. Therefore, the shippers need to share the correct VGM.  
  • It helps in calculating shipping rates. The heavier the container and cargo in it, the greater the cost. 
  • Cargo insurances require shippers to declare the correct container specification, such as container weight with cargo packed. 
  • VGM in shipping is a uniformly globalised solution for measuring shipping containers accepted worldwide. It allows shippers to measure and uniformly report container weight. 

How is VGM calculated in shipping? 

For calculating VGM in shipping, shippers need to consider the following entities- 

  • Weight of the cargo 
  • Weight of container packing material 
  • Any dunnage and bracing used for securing the cargo in its position 
  • Tare weight of the shipping container. 

By adding the weight of all the above-listed entities, shippers can calculate the verified gross mass of a container for shipping. 

Methods of calculating VGM in shipping 

There are two methods for calculating VGM in shipping. 

  1. Overall weight of container– To calculate the verified gross mass in shipping using this method, the shipper must weigh the entire container after it has been packed with all its content and packing material. 
  2. Weighing content and container separately– As the method suggests, shippers must weigh all the items inside the container individually, along with their packing. The weight of the packed cargo is then added to the container’s tare weight for calculating VGM in shipping. 

These methods of calculating VGM in shipping allow ocean carriers and terminal operators to conduct efficient cargo handling and container stowage. 

LOTUS Containers sells and leases different shipping containers, such as double doors, reefers, and 53-foot intermodal containers. You can even buy shipping containers from us to cater to diverse shipping needs.

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