How is efficiency defined on the calculator? Kelsey August 05, 2021 21:18 Updated The Grainfather recipe creator uses Brewhouse Efficiency to calculate the parameters of your recipe. Related articles How can I improve my efficiency? My beer has finished fermenting but is cloudy, what should I do? Is the 'batch volume' the final, end amount I'll finish up with? What is BU/GU? Where do I enter my mash water and sparge water volumes?