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 Home Brew Forums > Abv formula?

06-05-2012, 10:08 PM   #1
moobert88
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 Abv formula?

Is there a formula for predicting the ABV of a 5 gallon homebrew. I was just wondering how much extract to start buying for my first made from scratch extract brew, and I don't want it to turn out tasting like scotch!

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06-05-2012, 10:37 PM   #2
slarkin712
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The simple formula is this:
ABV% = (OG - FG)*131

For example, if my original gravity was 1.065 and my final gravity was 1.015 it would be:

ABV% = (1.065 - 1.015)*131 = 6.55%

You can always get some brewing software, use an online calculator, or get a phone app.

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06-06-2012, 12:10 AM   #3
moobert88
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I understand the of-fg equation. I was just wondering if there is a good rule of thumb for #'s of extract to % of alcohol.

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06-06-2012, 01:02 AM   #4
sweed
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Easiest place I figure it out, is the hopville beer calculus guide. Put in all your fermentables, hops, yeast etc, and it calculates it for you, before you brew. It is a estimate as it uses a 75% efficiency that I think can be changed?
For actually abv, get a hydrometer and do OG and FG readings.

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06-06-2012, 01:16 AM   #5
dennisjonesjr
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I use this: http://www.tastybrew.com/calculators/gravity.html

Boil volume: I usually use 2.5 gallons
Final volume: 5 gallons

for Grains used I just go with the Amber Dry Malt Extract (default) or Light Dry Malt Extract: 6 lbs should be a good start

This will give you a good rough guess.

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