Working out ABV - Home Brew Forums

 Home Brew Forums > Working out ABV

06-15-2011, 07:56 PM   #1
renshaw
Recipes

May 2011
Nottingham, Mansfield
Posts: 98

Just wondering what is the right equation to use.

I've used coopers beer kits they say
(OG-FG)/7.46 + 0.5=ABV%

Another i've read says: (OG-FG) /7.5 =ABV%
then i brought a set yesterday and it says this in the instructions

(OG-FG) /7.365 =ABV%

Because saying that OG was 1070 and ending was 1000 for each in order listed above we get the below results.

9.8
9.3
9.5

I was wondering what is correct?

Thank you.

06-15-2011, 08:02 PM   #2
beergolf

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Jan 2011
collingswood, nj
Posts: 6,052
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This formula works.

(OG-FG). X 131= ABV

06-15-2011, 08:07 PM   #3
renshaw
Recipes

May 2011
Nottingham, Mansfield
Posts: 98

Quote:
 Originally Posted by beergolf This formula works. (OG-FG). X 131= ABV
that does give a reading of 9.17 whats the lowest up to yet.

:S

06-15-2011, 08:22 PM   #4
VTBrewer
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Dec 2008
South Burlington, VT
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I think the x131 is the more commonly used one. It's in Papizan's book. I'm guessing howerever that all are well with in the margin of error of a calibrated hydorometer and the human eye.
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06-15-2011, 08:31 PM   #5
renshaw
Recipes

May 2011
Nottingham, Mansfield
Posts: 98

That is true, I do have two hydrometer,
i might drag my old en' out and see if it gives different reading to the new!
I'm guessing overall with the equations and human eye and hydrometer could make a various of around 1% ether way.

06-15-2011, 10:01 PM   #6
unionrdr
Heavyweight homebrewing author & air gun shooter

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Feb 2011
Sheffield, Ohio
Posts: 38,991
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I use the cooper's formula & my brain cells to compute ABV%. I'd say the cooper's formula is pretty close.
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06-15-2011, 10:09 PM   #7
gratefuldisc
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Oct 2009
CT
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