Oil prices are quoted per barrel (bbl). The abbreviation ‘bbl’ indicates one barrel of crude oil, but you may see Gbbl (one billion barrels), as well as Mbbl or Kbbl for one thousand barrels. For example, you can see that Brent crude oil spot prices are quoted by the barrel (bbl), as are West Texas Intermediate (WTI) oil prices on global futures exchanges like NYMEX.