There are two methods of obtaining a VGM:
- Method 1 involves weighing a loaded container.
- Method 2 involves weighing the contents of a container and adding this to the tare weight of the container.
In both methods, equipment meeting prescribed standards of accuracy must be used. The weighing equipment must either comply with existing requirements applicable to weighing equipment used for trade purposes under the National Measurement Act, or the equipment must be calibrated to accuracy standards approved by AMSA.
IMO circulars provide guidance to assist with compliance and implementation:
- MSC.1/Circular 1475 Guidelines regarding the verified gross mass of a container carrying cargo, as reproduced in Annex 1.
- MSC.1/Circular 1548 Advice to Administrations, port State control authorities, companies, port terminals and masters regarding the solas requirements for Verified Gross Mass of packed containers.
These IMO documents are not mandated in Australia, but provide guidance to all parties involved in the export of containers by sea, including broad guidance about common commercial scenarios that may arise.