The barrel of oil equivalent (BOE) is a unit of energy based on the approximate energy released by burning one barrel (42 U.S. gallons or 158.9873 litres) of crude oil. The BOE is used by oil and gas companies in their financial statements as a way of combining oil and natural gas reserves and production into a single measure, although this energy equivalence does not take into account the lower financial value of energy in the form of gas.
The U.S. Internal Revenue Service defines a BOE as equal to 5.8 × 106BTU. (5.8 × 106BTU59 °F equals 6.1178632 × 109J, about 6.1 GJ (HHV), or 1.7 MWh.) The value is necessarily approximate as various grades of oil and gas have slightly different heating values. If one considers the lower heating value instead of the higher heating value, the value for one BOE would be approximately 5.4 GJ (see ton of oil equivalent). Typically 5,800 cubic feet of natural gas or 58 CCF are equivalent to one BOE. The USGS gives a figure of 6,000 cubic feet (170 cubic meters) of typical natural gas.
A commonly used multiple of the BOE is the kilo barrel of oil equivalent (kboe or kBOE), which is 1,000BOE. Other common multiples are the million barrels per day, MMboed (or MMBOED, MMboepd), used to measure daily production and consumption, and the BBOe (also BBOE) or billion barrel of oil equivalent, representing 109 barrels of oil, used to measure petroleum reserves.