Barrel of Oil Equivalent (BOE) is a unit of energy used to compare different fuel types by converting them to the energy content of one barrel of crude oil. Since oil, natural gas, coal, and other energy sources are measured differently (barrels, cubic metres, tonnes), BOE provides a common basis for comparison. One BOE equals approximately 6,000 cubic feet of natural gas. Energy companies use BOE to report combined oil and gas production, and analysts use it to compare energy reserves and output across companies. The conversion standardizes energy discussions but involves approximations since energy content varies.