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Finding FG with OG and ABV - I no math

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TravelingLight

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Math is not my strong suit. I searched for this but couldn't find it. I want to know how to figure out FG when I know the OG and the ABV.

We all know to find ABV: (OG - FG) x 131 = ABV

But let's say I have a beer that I know is 1.064 OG and 7.8% ABV. How would I figure out the FG based on those numbers? So...

(1.064 - FG) x 131 = 7.8 <---Solve for FG
 
Math is not my strong suit. I searched for this but couldn't find it. I want to know how to figure out FG when I know the OG and the ABV.

We all know to find ABV: (OG - FG) x 131 = ABV

But let's say I have a beer that I know is 1.064 OG and 7.8% ABV. How would I figure out the FG based on those numbers? So...

(1.064 - FG) x 131 = 7.8 <---Solve for FG

(a-x)131=7.8

a-x=7.8/131

-x= 7.8/131 -a

x=a-7.8/131 [a=1.064]

= 1.064-0.0595

= 1.0045

OG ~1.005
 
Roughly....and you can back check your math with this site by plugging in what you come up with and comparing it to your estimated ABV:
http://www.brewersfriend.com/abv-calculator/


(1.064-FG) x 131 = 7.8

1.064-FG = 7.8/131 >> solve right side and then rearrange to get below

1.064 = .0595419 + FG >> solve for FG as below

1.064 - .0595419 = FG

FG = 1.004
 
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