Calculation of Brewhouse Yield
The brewhouse yield indicates how many percent of the grain amount was recovered as extract.
Calculation of brewhouse yield:
AS = Stw * SG * 0,96 * VA / Sch
AS: brewhouse yield in %
Stw: Original gravity in %w (°P)
SG: Specific Gravity
0,96: Correction factor
VA: Wort volume (hot) in liter
Sch: grain amount in kg
The wort volume is being measured by hot wort immedialtely after boiling, but prior to hop straining. This way, the hop remains are part of the measured volume. The best measuring instrument is a dipstick calibrated to the boil vessel.
The original gravity is also measured by hot wort using a lautering hydrometer or by cool wort with a standard hydrometer or refractometer. You should never use a standard hydrometer with hot wort - it could be destroyed by the heat.
The correction factor eliminates the failure vaused by the thermal expansion of the wort and vessel as well as the hot trub.
- Wolfgang Kunze: Technologie für Brauer und Mälzer, Fachbuchverlag Leipzig, 1962, Seite 257
- ebenda, Seite 263