- CO2 Extract Cans
GmAA = IBU x (BBL/0.8522)
GmAA = grams of alpha acids to be added
IBU = desired amount of bitterness units from the CO2 addition
BBL = barrels of finished beer
*Use rates may vary depending on the brewing process and the desired hopping level.
Homebrewers - if you are making a batch less than 1 barrel, you will need to divide the number of gallons by 31. The resulting decimal will be placed into the BBL box for calculations.