Taking the FG out of the bottle

[mmead]

For the sake of an accurate ABV, Could I use the FG from a pour after a month in the bottle?

 

[frazier]

How accurate do you need it to be?

Actually no, FG = gravity at the end of fermentation. Before bottling. Then when you add a known quantity of sugar for priming, the change (less than half a percent) of ABV can be calculated.

 

[TopherM]

You'll get close enough, but I would make this a one-time exception. As a habit, take FG at the end of fermentation.

HOWEVER, you can also get close enough by assuming that FG is about 75% of OG. Typical yeast under typical conditions have an average 75% attenuation rate. There might be a 5-6% varience on that attenuation, but that only equates to a few tenths of a point of ABV either way, so you can get close enough.

I haven't taken a FG reading in over two years, but then again I don't care if my beer is 5.7% ABV or 5.9% ABV as long as I know it tastes good and will give me a buzzzzzz

I just do 2-3 week primaries and have enough experience to know what it looks like when a fermentation is having an issues that needs attention, which is rare.

 

[Kahler]

If you do it from the bottle, you have to make sure the beer is flat. open it, let it sit for a while- overnight- and make sure there is NO carbonation. Carbonation will give you a fasle reading.

 

[ZombieBrew83]

+1 for carbonation messing up your reading. The bubbles can stick to your hydrometer after bottle conditioning giving you a higher FG than what it actually is.