Convert oil barrel to liter

Recipes give ingredients either by volume (millilitres, cups, spoons) or by weight (grams, ounces), and the two cannot be converted directly: the weight of a given volume depends on the ingredient. A cup of water weighs about 240 g, a cup of flour only about 125 g and a cup of sugar about 200 g. The link between the two is the density of the ingredient.

The oil barrel is 42 US gallons, 158.99 l, a size that goes back to the whisky and oil barrels of 1860s Pennsylvania. Crude oil is quoted per barrel (Brent, WTI) and production in barrels per day: the world produces about 100 million barrels a day, and a large tanker carries about 2 million. No physical barrels are involved; oil moves by pipeline and ship. A barrel of crude yields roughly 160 l of refined products in total, of which about 70–75 l is petrol.