Barrels (UK) to gallons (UK) conversion calculator shown above calculates how many gallons (UK) are in 'X' barrels (UK) (where 'X' is the number of barrels (UK) to convert to gallons (UK)). In order to convert a value from barrels (UK) to gallons (UK) (from bl to gal) just type the number of bl to be converted to gal and then click on the 'convert' button.