Basic Brewery calculations, short version ... Calculation of Specific Gravity (SGE) from %P of extract in...

Basic Brewery calculations, short version
NOV 2011
Calculation of Specific Gravity (SGE) from %P of extract in wort at 20 oC:
The extract content (kg extract / hl wort at 20 °C) in the wort will be:
kg Extract / hl cold wort = OE%P * SG
This however requires knowledge of the specific gravity (SG)
For quick & dirty calculation only:
SG = 1 + 0.004 * OE%P
This hipshot formula is better for weaker wort than for stronger.
Calculation of Brewhouse yield:
Brewhouse yield =
Amount of extract in finished wort / Amount of extract from brewing materials:
Large breweries expect yield > 98 %, and micro breweries may be > 85 %.
Calculation of mash thickness:
The proportion of brewing water to brewing materials is interesting as it indicates the
thickness of mash:
Water / Materials =
652.5 / 225 = 2.9 liter water / kg materials
Normal values for this figure for lautertun process will be in the range: 2.8 – 3.5
depending on the actual mashing recipe.
Volume of mash
As a rule of thumb 1 kg malt grits take up 0.8 l space in the mash.
Total mash volume will then be (using numbers from calculation of first wort extract):
652.5 + 0.8 x 225 = 832.5 liter (at 20 oC)
Calculation of OE in kettle full before boiling:
To calculate the OE in the wort kettle before boil, one must know the end gravity (SG),
end volume (after evaporation) and the end SG:
Beg SG = OE = End Volume * End SG / Beg Volume
Calculation of evaporation in wort kettle:
End volume (after boil) = 10 hls (before boil) * 36 / 40 = 9 hls.
In other words: 1hls has evaporated during the boil.
Calculation of hop dosing, simplified way only.
≈ 50% (brewery specific)
α-acid in hops pellets: 5 %
7 hl
5 % α-acid in hops
Kg hops per brew:
Wanted B.U. x brewsize (hl)
---------------------------------------------------% Utilisation x % α-acid in hops used
Dilution Formula
Dilution/gravity calculations including evaporation calculations in the brewhouse
are based on a simple formula using volumes in hls and Specific Gravity (SG):
Beg Volume * Beg SG=End Volume * End SG
(The SG numbers are SG Points, i.e. 1.060 SG = 60 gravity pts, 1.045 = 45 SG pts.)
By re-arranging this formula, we find:
Beg Volume=End Volume * End SG / Beg SG
Beg SG=End Volume * End SG / Beg Volume
End SG=Beg Volume * Beg SG / End Volume
End Volume=Beg Volume * Beg SG / End SG
Degree of fermentation:
The apparent degree of fermentation (ADF) is the value, you read using the
saccharometer. The ADF is approx. = 1.24 * real degree of fermentation (RDF).
Craft formula: Useful for breweries with limited laboratory instrumentation.
Alcohol calculation from OE: The Craft Formula
In small breweries the instrumentation in production and in the laboratory may only allow
for measurement of gravities.
A hydrometer (saccharometer) may be used to measure the strength of the wort before
fermentation (OE%P) and the apparent extract (EA%) in the beer during processing and
in the final beer. As long as no sugar, syrup or water is added to the beer in the tanks,
the following new formula will calculate the Percent of Alcohol by Volume (A%vol):
A%vol=(OE%P - EA%) / (2.048 - 0.0126*OE%P)
( “The Craft Formula”)
Abbreviations used above
Original extract in percent Plato
Percent of Real Extract
Percent of Apparent Extract
Percent of Alcohol by mass
Percent of Alcohol by Volume
Specific Gravity of the Alcohol-containing distillate
Specific Gravity of the Extract-containing reminiscence
Specific Gravity of the Beer
ml/100 ml
g/ml over g/ml
g/ml over g/ml
g/ml over g/ml
One Pasteurisation Unit (PU) is defined as the heat received by 60oC in 1 minute. The
precise connection is defined as:
PU = time * 1.393 (Temp. – 60)
Time is measured in seconds/60
Temperature is measured in °C.
In stead of using this formula, you may simply use this diagramme: