Convert Barrel (Oil) (bbl (oil)) to Gallon (US) (gal (US)) instantly.
About these units
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.
Gallon (US) (gal (US))
The US gallon is defined as exactly 231 cubic inches, or 3.785411784 liters. It is widely used in American commerce for gasoline, milk, water, and other household liquids. Its historical roots lie in old English wine and ale gallons, whose varying definitions ultimately led to divergent US and UK systems. Today, the US gallon remains deeply embedded in American culture, especially in automotive contexts—fuel economy ratings such as "miles per gallon" (MPG) illustrate its everyday relevance. Despite the global shift toward metric volume units, the US gallon persists due to familiarity and regulatory inertia. It remains an iconic unit, symbolizing uniquely American measurement traditions.