How to estimate FG? - Home Brew Forums

 Home Brew Forums > How to estimate FG?

08-03-2006, 05:04 PM   #1
Todd
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Jun 2006
Mechanicsburg PA
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When you are setting up a recipie is there a way to determine what the FG should be? I know we can get the OG estimate. I suppose there is probably a formula based off the type of yeast?

08-03-2006, 05:15 PM   #2
SBN
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May 2006
Grayslake, IL
Posts: 104

Todd - the way it was explained to me, when I asked the same question, was to take your OG times your yeast attenuation - so a 75% attenuating yeast - working optimally - on a wort of, say, 1.06 would be finished at 1.015........

Skol!

08-03-2006, 05:59 PM   #3
Todd
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Jun 2006
Mechanicsburg PA
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Quote:
 Originally Posted by SBN Todd - the way it was explained to me, when I asked the same question, was to take your OG times your yeast attenuation - so a 75% attenuating yeast - working optimally - on a wort of, say, 1.06 would be finished at 1.015........ Skol!
That is what I thought, thanks. makes sense to me.

08-16-2010, 08:50 PM   #4
HItransplant
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Aug 2010
Portlandia
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I cant figure out how 75% multiplied by 1.060 comes out to 1.015. can anyone give me more specific information on this formula.. Im obviously missing something.

thanks,
HIt

08-16-2010, 08:51 PM   #5
JLem

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Jan 2009
Attleboro, MA
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it's actually OG - (OG x attenuation) --> 60 - (60x75%) = 15
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Reason: fixed spelling error

08-16-2010, 08:56 PM   #6
jamesjensen1068
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Jan 2010
Omaha, NE
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Take the number 1.060 and use just the last two numbers "60"

60 x .75 = 45

60 - 45 = 15

Thus your number for FG would equal 1.015

Cheers

08-16-2010, 09:15 PM   #7
TipsyDragon
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Mar 2009
California
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every yeast has a attenuation RANGE ratting ... most software uses an average of this range when spitting out an FG and never take fermentability into account. i would use the above formula for both the upper and lower limits for the yeast in question. that way if you don't hit your exact number you wont panic because you are hopefully within the right range. remember real life almost never matches what the math tells you.

08-16-2010, 09:25 PM   #8
jamesjensen1068
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Omaha, NE
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The other formula that you can use would be to divide by 4.

OG 1.060 (60 / 4 = 15)

So final gravity = 1.015

08-16-2010, 09:36 PM   #9
JLem

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Quote:
 Originally Posted by jamesjensen1068 The other formula that you can use would be to divide by 4. OG 1.060 (60 / 4 = 15) So final gravity = 1.015
though that only works for a 75% attenuation
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08-16-2010, 09:53 PM   #10
ajf
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Oct 2005
Long Island
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Also, the published attenuation figures for different yeasts can be wildly inaccurate for your own fermenting conditions.
With WLP002, the published attenuation is 63% to 70%. I routinely get 75% - 80% with that yeast.
The only way I know of that works is to keep records, and base your forecasts off your previous results. Of course, this doesn't work very well if it is the first time you have used a yeast, or if you change your mash in some way that would affect attenuation.

-a.
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