Figure out FG ? - Home Brew Forums

 Home Brew Forums > Figure out FG ?

09-08-2011, 07:37 PM   #1
karljrberno
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May 2011
New Haven, MI
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Is there a way to determine what the FG Of you beer will be ?

I know there is factor all grain / extract any good reads on this how to determine

09-08-2011, 07:45 PM   #2
Nateo

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Jul 2010
Bennett Springs, MO
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There's no good way to accurately predict it before you brew, but you can find out for sure on each batch by doing this:
http://braukaiser.com/wiki/index.php/Fast_Ferment_Test

That will tell you your limit of attenuation.
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09-08-2011, 08:01 PM   #3
temptnmonkey
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Jun 2011
Omaha
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turn the 1.060 into 60, and the % into .75 and you can simply do the following formula

60 - (60 * 0.75) = 15 (don't forget to add the 1.0). so, the est. FG is 1.015 (and give or take a couple points).

There are many other formulas (variations on the same thing) and free/paid software that will do it for you available as well.

09-08-2011, 08:21 PM   #4
Nateo

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Bennett Springs, MO
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Attenuation for brewer's yeast generally ranges from 65-85%, and could be 60-90% if using lots of simple-sugar adjuncts or lots of unfermentables. That's a big range. For a "normal" beer, with an OG of 1.060, the range would be between 1.09-1.021, which is so large as to be practically useless.

To just pick 75% attenuation as your estimate is a sure way to be wrong almost all of the time.

If you have specs for the yeast strain you're using, it's a good start. For instance, the expected attenuation for WLP001 is 63-70%, so the beer in our example would finish between 1.018-1.022, which is a much more reasonable range, but is still a larger range than I feel comfortable trusting.
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09-08-2011, 09:35 PM   #5
TopherM

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Mar 2011
St. Petersburg, FL
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Hydrometer. Also, most recipes include the expected FG.
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09-08-2011, 10:01 PM   #6
Qhrumphf
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Apr 2011
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Only way to get a really good idea is to repeat recipe and same process, and even then it'll only work for that one brew and won't always be exact. I routinely get higher than any given yeast's attenuation ratings and drop lower than software's FG estimates by a few points. So I just adjust my recipes assuming that to be the case and it typically works out ok.

That said, I've found that extract/steeping grain recipes tend to be a bit more predictable than AG or PM recipes, as the grain and the mash add a bunch of extra variables to the equation. Not saying I know why or that that's always the case, just my experience.
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