Imperial Gallons to Oil Barrels (gal (UK) to bbl)

1 imperial gallon equals 0.02859404585 oil barrels (rounded).

1 imperial gallon = 0.02859404585 oil barrels

How to convert imperial gallons to oil barrels

To convert imperial gallons to oil barrels, multiply the number of imperial gallons by 0.02859404585. The factor is rounded to 10 significant digits. To go the other way, multiply oil barrels by 34.97231575 (rounded).

oil barrels = imperial gallons × 0.02859404585

Example: 10 imperial gallons = 0.2859404585 oil barrels.

Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.

About these units

Imperial Gallon (gal (UK))

Imperial (British)Current unit

Exactly 4.54609 liters, the volume of 10 pounds of water. Used for fuel economy in the UK (miles per gallon) and historically across the Commonwealth.

Britain unified its confusing gallons by act of Parliament in 1824. Before then, the country used separate ones for wine at 231 cubic inches, ale at 282 and corn at about 268.8. The 1824 reform replaced them with the imperial gallon, defined as the volume of ten pounds of distilled water, calculated at 277.274 cubic inches. A new definition in 1889 slightly changed that, and after the liter was restored to exactly a cubic decimeter in 1964, Canada and then the UK in 1976 adopted the exact value of 4.54609 liters.

Because the United States kept the 231-cubic-inch wine gallon, an imperial gallon is about 20 percent larger than a US gallon. That explains why a car rated at 40 miles per gallon in Britain is less impressive in American terms, since it comes to roughly 33 US miles per gallon. Ireland dropped the gallon as a primary trade unit at the end of 1993 and the UK at the end of September 1995, but it lives on in British fuel-economy figures and older recipes.

1 imperial gallon = 4.54609 liters (exactly).

Sources: Wikipedia: Gallon; UK Weights and Measures Act 1985, Schedule 1

Oil Barrel (bbl)

US customaryCurrent unit

Exactly 42 US gallons (158.987 L). The unit of crude oil trade since the 1860s Pennsylvania oil fields.

The oil barrel did not come from the oil industry's own design but from the barrels already lying around Pennsylvania. After Drake's well of 1859 started a boom, producers shipped crude in whatever containers were handy: whiskey barrels of around 40 gallons, plus 42 and 45 gallon casks. Buyers grew suspicious of the inconsistency, and around 1866 producers settled on the wine tierce of 42 gallons, two gallons bigger than the common whiskey barrel. An Oil City circular of August 1866 also promised an allowance of two gallons in every 40.

By 1872 the 42-gallon standard was firmly established, and US government bodies adopted it in 1882. The barrel is exactly 42 US gallons, about 159 liters, and remains the worldwide pricing unit for crude, even though many countries report volumes in cubic meters. EIA says Strait of Hormuz flows of 20 million barrels a day equal about a fifth of global consumption, implying roughly 100 million barrels a day. The abbreviation bbl has a disputed origin: a popular story links it to Standard Oil's blue barrels, but the abbreviation predates the oil industry.

1 oil barrel = 158.9872949 liters (approximately).

Sources: Wikipedia: Barrel (unit); NIST SP 811, Appendix B.8: conversion factors for volume; EIA: Today in Energy, Strait of Hormuz oil flows

Related conversions

See all volume units.