Confusion in calculating my ABV - Home Brew Forums

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 Home Brew Forums > Confusion in calculating my ABV

02-10-2013, 12:40 AM   #1
grovedude
Recipes

Nov 2012
San Francisco, CA
Posts: 7

Totally newbie question here - and I've even tried searching for the answer but nothing has done the trick. (Maybe I am dense?)

I am trying to calculate my % ABV, and failing. So I took photos in the hope that someone here could teach me.

The photo (which I am going to try to attach here) shows before and after.

Before = minutes before I pitched the yeast
After = 7 days later when I racked it

This is an experimental brew- I am using a Chimay-style of recipe, but instead of Belgian Candy Sugar, I am using agave syrup (not nectar, I actually got it from a friend's tequila distillery in Mexico and brought it home with me. It's the stuff they make tequila out of, direct from the oven.)

Can anyone help me? I think, based on the readings, my experiment may have produced a beer that is extremely low in alcohol.

02-10-2013, 12:47 AM   #2
woody34
Recipes

May 2012
Posts: 132
Liked 19 Times on 11 Posts

1.072 and 1.030. I use Rooftopbrew website and enter those numbers in their ABV calculator. You probably haven't reached final gravity yet though as its only fermented a week.

02-10-2013, 12:47 AM   #3
iaefebs
Registered User
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Aug 2010
West Coast, MI
Posts: 2,670
Liked 245 Times on 177 Posts

Based on a 1.074 OG and a 1.030FG your ABV would be5.8%

02-10-2013, 12:50 AM   #4
grovedude
Recipes

Nov 2012
San Francisco, CA
Posts: 7

It's still bubbling in the secondary now, so I wonder how high it is likely to go. Thanks for helping me out - I think I see what you're reading now.

02-10-2013, 01:02 AM   #5
woody34
Recipes

May 2012
Posts: 132
Liked 19 Times on 11 Posts

You certainly didn't make a weak beer. Your final grav may get down below 1.020. You would have a 7 plus ABV.
Just rough estimates.

02-10-2013, 01:08 AM   #6
iaefebs
Registered User
Recipes

Aug 2010
West Coast, MI
Posts: 2,670
Liked 245 Times on 177 Posts

Quote:
 Originally Posted by grovedude It's still bubbling in the secondary now, so I wonder how high it is likely to go. Thanks for helping me out - I think I see what you're reading now.
It's more of a how low will it go. Not knowing what you are looking for I'm guessing you are wanting a beer to finish around 1.020 which is 7.1%

02-10-2013, 01:10 AM   #7
grovedude
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Nov 2012
San Francisco, CA
Posts: 7

Thanks! I love this forum!!!!

02-10-2013, 01:13 AM   #8
weirdboy
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May 2009
Los Angeles
Posts: 8,199
Liked 488 Times on 394 Posts

A simple rule of thumb is to use this equation:

ABV% = (OG - FG) * 131

ABV% = (1.072 - 1.030) * 131 = 5.5

There are other formulas out there, and calculating the actual ABV can actually get quite complicated if you look into the details, but that approximation works well for most beers.

02-10-2013, 01:16 AM   #9
heckler73
Recipes

Feb 2012
North Vancouver, BC
Posts: 382
Liked 37 Times on 30 Posts

don't bother with math. that's for university dayze...

http://www.brewersfriend.com/abv-calculator/

02-10-2013, 01:31 AM   #10
weirdboy
Recipes

May 2009
Los Angeles
Posts: 8,199
Liked 488 Times on 394 Posts

Quote:
 Originally Posted by iaefebs I like how different people read the same scale 3 different ways while everyone read the 1.030 current. I have to ask weirdboy, how did you come up with seeing a 1.068?
Sorry, it was 1.072...I meant to change that number in my other post. I guess I ought to do that so as not to cause more confusion.