Percent Alcohol calculation

[oppigards]

I calculate (OG-FG)*0,132 to get % alcohol by volyme. This formula is approved by the Swedish Tax. But I have seen breweries calculate with 0,127 and this website has a calculator which use 0,130. Should I revise my calculation?

[matt]

Calculation of Alcohol streangth

(OG-PG) x f = %ABV

"The value of 'f' is not constant because the yeild of alcohol is not constant for all fermentations. In lower streangth beers, more of the sugars available for fermentation are consumed in yeast reproduction than in producing alcohol"

Some factors produced by the Lab of Goverment chemist(U.K.)

(OG - PG)..... %ABV ......Factor
10.5 - 17.2.. 1.3 - 2.1 ... 0.127
26.2 - 36.0 .. 3.3 - 4.6 ... 0.129
36.1 - 46.5.. 4.6 - 6.0 ... 0.130
57.2 - 67.9.. 7.5 - 9.0 ... 0.132

Recommend you verify your calculation with an analysis of your beer on a regular basis. (e.g., once a year)
matt

[Alex T]

Hi,

For ABV, I use:

(OG-PG) x 0.52945

with gravity being in Plato. However, where I work we analyse all alcohols by distillation as calculations are always just around-about.

Cheers!

Alex

[Ted Briggs]

I use the following from "Malting and Brewing Science":
(Og-Fg)X .516 with gravity measured in *Plato.
Interesting there is controversy on this. Remember though, that final reading is apparent extract and not real. I was using a rounded .52 but switched. Anyways, for a pub brewer its close enough!

[matt]

Original response and Factors are for Specific gravity.
There is approximately 4 degrees Specific gravity for 1 Plato.
If you convert the plato factors(divide by 4) you have the Specific gravity factors;

.52945 / 4 = 0.132...

.516 / 4 = 0.129