Convert barrels to gallons

A barrel of oil holds 42 US gallons. That figure is a definition, not a rounded measurement, so the formula is simple: gallons = barrels × 42. Ten barrels make 420 gallons and a thousand barrels make 42,000 gallons[1].

Other barrels hold less or more. US federal tax on beer is based on a barrel of 31 gallons[2]. A British beer barrel holds 36 gallons, but they are imperial gallons, and each one is about a fifth bigger than a US gallon[3]. In US gallons that same barrel comes to 43.234.

You set both units with the switches under the fields. Barrel type offers Oil, US beer, US liquids and UK beer, and Gallon type offers US and UK / Imperial. Switch an oil barrel to imperial gallons and you get 34.972, while the symbol next to the result changes from US gal to UK gal.

To go the other way, use the gallons to barrels converter. If you need the gallon itself in metric, the gallons to litres converter has the same US and imperial switch.

An oil barrel, symbol bbl, is a unit of volume rather than a container. Crude travels by pipeline and tanker, yet prices, output and reserves are still counted in barrels[3]. When a news report says a country pumps a million barrels a day, it means 42 million US gallons of crude.

The gallon comes in two sizes. The US gallon is 231 cubic inches, or 3.785 litres, while the British imperial gallon is defined as the volume of ten pounds of water and works out at 4.546 litres[1]. The oil barrel is defined in US gallons, so oil figures use them wherever they are published. Pick UK / Imperial when your figure comes from a British brewery or an older British document.

Why 42? After the first Pennsylvania well in 1859, crude was sold in barrels of any size, and buyers did not trust them. Around 1866 local producers agreed to sell by the gallon, and in 1872 their association adopted the 42-gallon barrel, the size of an old English wine cask called the tierce, as the standard[3].

No. The steel drum used for oil and chemicals holds 55 US gallons in the United States and 200 litres elsewhere, so it is bigger than an oil barrel[3]. A 55-gallon drum is 1.3095 barrels, and a 200-litre drum is 52.83 US gallons, or 1.258 barrels.

So when someone points at a drum in a yard, they mean a container. When someone quotes the price of oil, they mean 42 gallons.

Divide the barrel price by 42. At 70 dollars a barrel, a gallon of crude costs 1.67 dollars. In countries that sell fuel by the litre, such as the UK, Canada and Australia, divide by 158.99 instead, which gives 0.44 dollars a litre.

That is the price of the raw material, not of fuel at the pump. A gallon of gasoline also carries the cost of refining, transport, taxes and the retailer's margin, so the barrel price alone cannot tell you what you pay at the station.