Gross Registered Tonnage (GRT) is a measure that calculates the total internal volume of space available within the hull and enclosed areas above deck of a merchant vessel. It is used to assess the vessel’s capacity for cargo, passengers, stores, fuel and crew. As an indicator of a ship’s size and carrying capacity, GRT helps shipping companies to determine its suitability for particular routes and to comply with regulatory requirements. It is an important metric in the maritime industry for operational planning and regulatory compliance.