Billion cubic metres of natural gas (abbreviated: bcm) or cubic kilometer of natural gas is a measure of natural gas production and trade. Depending of implied standards, this measure may represent different value of energy content. According to the standard defined by the International Energy Agency, it corresponds in average to 38.2 petajoules (1.06×1010 kWh) of energy in the case of Russian natural gas and 41.4 petajoules (1.15×1010 kWh) of energy in the case of Qatar's natural gas.^[1]

According to the standard defined by the International Energy Agency, the gas physical volume is used, which is measured at the temperature of 15 °C (59 °F) at atmospheric pressure. According to the Russian standard, the gas volume is measured at 20 °C (68 °F). That means that 1 billion cubic metres of natural gas by the International Energy Agency standard is equivalent to 1.017 billion cubic metres of natural gas by the Russian standard.^[1]

Some other organizations use an energy equivalent-based standards. BP uses a standard which is equivalent to 41.87 petajoules (1.163×1010 kWh) per billion cubic metres. Cedigaz uses a standard which is equivalent to 40 petajoules (1.1×1010 kWh) per billion cubic metres.^[1]