Estimate final gravity

[AGBrewer]

How do you do it?

 

[homebrewer_99]

Record your brews OG reading, ex: 1.054

Record your brews FG reading, ex: 1.012

Subtract FG from OG, ex: 42. Equals gravity.

42 (actually .042) * 105 = 4.410% ABW (alcohol by weight)

4.410 * 1.25 = 5.51% ABV (alcohol by volume)

 

[AGBrewer]

Record your brews OG reading, ex: 1.054

Record your brews FG reading, ex: 1.012

Subtract FG from OG, ex: 42. Equals gravity.

42 (actually .042) * 105 = 4.410% ABW (alcohol by weight)

4.410 * 1.25 = 5.51% ABV (alcohol by volume)

So is it not possible to estimate Final Gravity based on the recipe?
I know how to calculate ABV

 

[Professor Frink]

It depends on the attenuation of the yeast strain you're using. If your yeast is 75% attenuation, then it will be .75xOG

 

[Brewsmith]

It depends on the attenuation of the yeast strain you're using. If your yeast is 75% attenuation, then it will be .75xOG

Actually it will be 0.25xOG

 

[Nostrildamus]

And if the decimal points confuse you like they do me, work in GUs or simply knock off the 1.0 and do like Brewsmith said.

1.055 = 55 GU * 0.25 = 13.75 or 1.01375

 

[AGBrewer]

Makes sense, thank you

 

[Orfy]

or to simplify

(Gravity-1000)-((Gravity-1000)*Attenuation rate%)+1000

(1055-1000)-((1055-1000)*75%)+1000=1013.75

 

[homebrewer_99]

So is it not possible to estimate Final Gravity based on the recipe?

My answer for "estimating" would be yes based upon expected attentuation.

Is the answer correct? No.

Why? Unless you check your gravities with a hydrometer it is all a guess.

The MAJOR problem one may encounter by guessing is bottle grenades due to overpriming (even if the correct amount of sugar was used) due to a stuck fermentation; i.e., your fermentation was not complete thus bottling too soon.

So why guess.

When you know your brew you know all the answers and no surprises or excuses are necessary.

My point is almost EVERYTIME you sample ones wares a brewer will say things like, well, it would be better if... My reply is if it's not ready, it's not ready. Simple.

 

[AGBrewer]

I always check sg before I bottle/keg, I was just curious as to the ballpark abv that I will get out of the hop rod rye clone I just finished. I agree with you, know your brew.
EDIT: Hey you edited

 

[malkore]

it only takes one glass grenade before you bow down to the mighty power of the hydrometer.

its messy, it wastes beer, and its potentially dangerous to handle bottles on the verge of bursting.

 

[homebrewer_99]

it only takes one glass grenade before you bow down to the mighty power of the hydrometer.

its messy, it wastes beer, and its potentially dangerous to handle bottles on the verge of bursting.

I agree.

If anyone is interested, I made up an Excel spreadsheet of calculated gravities. I printed it out and placed it in a doc protector in a binder for easy reference. Email me if you want a copy of the file: [email protected]