From the HBD Archive
From: mlh@cygnus.ta52.lanl.gov (Michael L. Hall)
Subject: Re: Calories in homebrew
Date: 1992-06-03 17:11:10 GMT

I know that there have already been answers to this question, including
disclaimers by George Fix and a nice linearized version with analysis
by Robert Bradley, but I thought someone might like to see yet another
version of the formulas. These are the same formulas that George Fix
gave, except that they have been converted to FG and OG (using the
Plato to SG (divide by four) conversion that is not exact acording to
George). This is probably what Robert did, before he linearized them.
Anyway, here they are:

Note that OG and FG are used in the full form (e.g. 1.045). C stands for
the calorie content per 12 ozs., and the {alc} and {ext} subscripts signify
the fractions from alcohol and extract respectively.

Other definitions:

A = alcohol content of finished beer in % by weight.
RE = real extract of finished beer in degrees Plato.
OG = original gravity of the beer.
FG = final gravity of finished beer.

76.8 (OG - FG)
A = --------------
(1.775 - OG)

RE = 250 (0.1808 OG + 0.8192 FG - 1)

(OG - FG)
C_{alc} = 1881.22 FG ------------
(1.775 - OG)

C_{ext} = 3550 FG (0.1808 OG + 0.8192 FG - 1.0004)

C = C_{alc} + C_{ext}

[ 0.53 (OG - FG) ]
C = 3550 FG [ -------------- + (0.1808 OG + 0.8192 FG - 1.0004) ]
[ 1.775 - OG ]


Mike Hall
hall@lanl.gov

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