Understanding Efficiency

Efficiency is a commonly discussed subject among all grain brewers. But with the abundance of definitions for it, it easily becomes a matter of comparing apples with oranges. This article tries to shed some light on the various efficiency definitions that are in place and how they are defined (sometimes differently, depending on the author).

In "How To Brew", John Palmer defined the brewing efficiency as the ratio between the gravity points of the wort in the kettle and the maximum potential (labratory extract) of the grain. The maximum potential of the grain is given in gravity units per pound and gallon. Based on that the gravity points of the kettle wort are:

kettle gravity points = brewing efficiency * grain amount in pound * kettle volume * potential of the grains

When grains with different potential are used, the weighted average of their potential needs to be used in the above equation.

Daniels: Defines Mash efficiency as the ratio between total gravity of wort (GU * volume) and the total potential of the grains

Narziss: Defines Sudhausausbeute (brew house efficiency) as the ratio between the amount of extract that made it into the boil kettle vs. the amount of grain that was used.

BYO Wizard: Defines brewhouse efficiency the same as Narziss does. He also defines brewhouse yield as the ratio between the brewhouse efficiency and the weighted average of the grains laboratory yields.

Beersmith: defines 3 types of efficiency: brewhouse efficiency based on target volume, efficiency into boiler, efficiency into fermenter:

OBY (overall brewhouse yield): defines how close to the laboratory extract did mashing and lautering get.