How To Convert Barrel To Gallons

Please note that oil barrels and fluid barrels (beer etc) are different measurement units.

1 Barrel [Fluid] = 31.5 Gallons [US, Fluid]

1 Barrel [Oil] = 42 Gallons [US, Oil]
1 Barrel [Dry] = 26.24975569 Gallons [US, Dry]