The barrel of oil equivalent (BOE) is a unit of energy based on the approximate energy released by burning one barrel (42 US gallons, 35 imp gal or about 159 litres) of crude oil.
The U.S. Energy Information Administration defines the barrel of oil equivalent as about 6 gigajoules (1.7 megawatt-hours; 5.7 million British thermal units).
Typically 5,800 cubic feet of natural gas is equivalent to one BOE.
[2] Due to the risk of confusion The Society of Petroleum Engineers recommends in their style guide that abbreviations or prefixes M or MM are not used for barrels of oil or barrel of oil equivalent, but rather that thousands, millions or billions are spelled out.
Typically 1 tonne of oil has a volume of 1.08 to 1.19 cubic metres (6.8 to 7.5 bbl).