Barrel (unit) continued to use the same size barrels. In the worldwide oil industry, an oil barrel is defined as 42 US gallons, which is about litres or 35 imperial gallons. Oil companies that are listed on American stock exchanges typically report their production in terms of volume and use the units of bbl, Mbbl (one thousand barrels), or MMbbl (one million barrels) and occasionally for widest comprehensive statistics the Gbbl (or sometimes Gbl) denoting a billion. There is a conflict concerning the units for oil barrels (see ). For all other physical quantities, according to the International System of Units, the
Firkin (unit) a barrel and its value depends on the current size of a barrel, but at present: 1 firkin = 0.25 barrel = 9 imperial gallons = 10.8 U.S. gallons = 41 litres Firkin (unit) A firkin is a unit of volume or mass used in several situations. Its etymology is likely to be from the Middle English "ferdekyn", probably from the Middle Dutch diminutive of vierde ‘fourth’ (a firkin originally contained a quarter of a barrel). A firkin is an American unit of dry measure. 1 firkin = 9 US gallons = 34 litres. A firkin was a British unit