Rebel Brewer Giveaway!
 Home Brew Forums > How to estimate FG?

08-03-2006, 06:04 PM   #1
Todd
Feedback Score: 0 reviews
Recipes

Join Date: Jun 2006
Location: Mechanicsburg PA
Posts: 593
Liked 1 Times on 1 Posts

 How to estimate FG?

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, 06:15 PM   #2
SBN
Feedback Score: 0 reviews
Recipes

Join Date: May 2006
Location: Grayslake, IL
Posts: 106

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, 06:59 PM   #3
Todd
Feedback Score: 0 reviews
Recipes

Join Date: Jun 2006
Location: Mechanicsburg PA
Posts: 593
Liked 1 Times on 1 Posts

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, 09:50 PM   #4
HItransplant
Feedback Score: 0 reviews
Recipes

Join Date: Aug 2010
Location: Portlandia
Posts: 1,026
Liked 6 Times on 5 Posts
Likes Given: 6

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, 09:51 PM   #5
JLem
naturally selected
Feedback Score: 0 reviews

Recipes

Join Date: Jan 2009
Location: Attleboro, MA
Posts: 3,554
Liked 151 Times on 135 Posts
Likes Given: 4

it's actually OG - (OG x attenuation) --> 60 - (60x75%) = 15

Last edited by JLem; 08-16-2010 at 10:06 PM. Reason: fixed spelling error

08-16-2010, 09:56 PM   #6
jamesjensen1068
Feedback Score: 0 reviews
Recipes

Join Date: Jan 2010
Location: Omaha, NE
Posts: 366
Liked 8 Times on 8 Posts
Likes Given: 1

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, 10:15 PM   #7
TipsyDragon
Feedback Score: 0 reviews
Recipes

Join Date: Mar 2009
Location: California
Posts: 2,599
Liked 17 Times on 15 Posts

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, 10:25 PM   #8
jamesjensen1068
Feedback Score: 0 reviews
Recipes

Join Date: Jan 2010
Location: Omaha, NE
Posts: 366
Liked 8 Times on 8 Posts
Likes Given: 1

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, 10:36 PM   #9
JLem
naturally selected
Feedback Score: 0 reviews

Recipes

Join Date: Jan 2009
Location: Attleboro, MA
Posts: 3,554
Liked 151 Times on 135 Posts
Likes Given: 4

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
__________________
My Hombrewing Blog

My Beer Cellar

08-16-2010, 10:53 PM   #10
ajf
Senior Member
Feedback Score: 0 reviews

Recipes

Join Date: Oct 2005
Location: Long Island
Posts: 4,582
Liked 88 Times on 82 Posts
Likes Given: 37

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.

__________________

There are only 10 types of people in this world. Those that understand binary, and those that don't.