Is it me or the brewtoad calculation /regarding the alcohol/ doesnt make sense? - Home Brew Forums

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 Home Brew Forums > Is it me or the brewtoad calculation /regarding the alcohol/ doesnt make sense?

06-16-2013, 11:44 AM   #1
Elysium
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Feb 2013
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I have just brewed 2 different batches and used brewtoad to create the recipes...but I think the alcohol part of the recipes is not okay.

My OG: 1.053
FG: 1.016

I thought the equation is (OG-FG)*105...which leaves me with: 3.85

While the recipe tells me 4.8%.

Here is the actual recipe... http://www.brewtoad.com/recipes/1st-biab

Am I wrong or the site gives the wrong ABV?

06-16-2013, 12:16 PM   #2
SixStrings
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Aug 2012
, VT
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I believe that formula is for alcohol by weight, not by volume.

The formula I use is (og - fg) * 131, which puts your ABV at 4.84%, or roughly the same as brewtoad's estimate.

06-16-2013, 09:47 PM   #3
Elysium
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Feb 2013
Posts: 1,187
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Quote:
 Originally Posted by SixStrings I believe that formula is for alcohol by weight, not by volume. The formula I use is (og - fg) * 131, which puts your ABV at 4.84%, or roughly the same as brewtoad's estimate.
The formula I got is from an old book...and there the multiplier is 105. Thanks for the info. I guess it is 131 that I have to use. I'll do a bit of a searching for more info on this.

06-16-2013, 09:50 PM   #4
Yooper
Ale's What Cures You!

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Jun 2006
UP of Michigan, Winter Texan
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Quote:
 Originally Posted by Elysium The formula I got is from an old book...and there the multiplier is 105. Thanks for the info. I guess it is 131 that I have to use. I'll do a bit of a searching for more info on this.
Yes, 105 as a multiplier is the formula for alcohol by weight (ABW). The formula for alcohol by volume (ABV) is x 131.
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06-16-2013, 10:21 PM   #5
Elysium
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Feb 2013
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Quote:
 Originally Posted by Yooper Yes, 105 as a multiplier is the formula for alcohol by weight (ABW). The formula for alcohol by volume (ABV) is x 131.
Yooper...soon you will become my "beer-guardian-angel"...since you answer soooo many of my questions. :P

Anyway...can you tell me what the difference is? I thought there is only one way to describe the alcohol content of a beer. What are this volume/weight things?

06-17-2013, 12:23 PM   #6
Yooper
Ale's What Cures You!

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UP of Michigan, Winter Texan
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Quote:
 Originally Posted by Elysium Yooper...soon you will become my "beer-guardian-angel"...since you answer soooo many of my questions. :P Anyway...can you tell me what the difference is? I thought there is only one way to describe the alcohol content of a beer. What are this volume/weight things?
It's just what it says- another way to express alcohol content. Most labels in the US show "alcohol by volume", but "alcohol by weight" is used as well.

The ABV shows the amount of alcohol by the total volume, while the alcohol by weight is the percentage of weight.

To convert ABW to ABV, simply multiply the ABW by 1.25.
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