Convert Ton Register (ton reg) to Barrel (Oil) (bbl (oil)) instantly.
About these units
Ton Register (ton reg)
A register ton, or ton register, is a unit of volume, not mass, equal to 100 cubic feet. It is used in maritime contexts to measure the internal capacity of ships—specifically cargo-carrying volume, not weight. Ship registries rely on register tons to calculate taxes, port fees, and cargo classifications. The unit dates back to 19th-century maritime law, where consistent volumetric measurement was critical for international shipping regulation. Despite changes in global trade and containerization, register tons remain important for historical vessel documentation, as well as for understanding older merchant and naval ship specifications.
Barrel (Oil) (bbl (oil))
An oil barrel is defined as 42 US gallons, or 158.987 liters, and is a fundamental unit in the petroleum industry. This peculiar size traces back to the early Pennsylvania oil fields, where producers standardized whiskey barrels and modified wooden casks for oil transport. The need for consistent trade volumes cemented the 42-gallon barrel as the industry norm. Today, global oil production, pricing, and consumption are expressed in barrels—from daily OPEC reports to energy market forecasts. Even though oil is no longer physically shipped in barrels, the unit remains deeply embedded in international energy economics.