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Alcohol calculation

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lovebrewin

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So I'm pretty new to this.. To get an accurate alcohol% measurement of your beer do you just use your hydrometer reading at bottling or do you test it when it's fully conditioned and carbonated in the bottle. Reason I ask is obviously there is still yeast activity in the bottle thus pulling the sg down further..
 

MalFet

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Most estimations of alcohol on the homebrew level are based on a comparison of OG and FG. In other words, you measure the quantity of sugar that has been consumed and extrapolate alcohol production from that. There are a few assumptions intrinsic to this, but it generally works well enough for our purposes.

There should really be only a very little bit of fermentation happening in the bottle. If the FG drops by any significant amount, you're going to start seeing bottles explode.
 

feinbera

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Take one reading right before you pitch your yeast. This is your original gravity.

Take another reading about a week after visible signs of fermentation have subsided, then, wait a two or three days, and take a third reading. If the second and third readings are the same, your beer is done, and you have your final gravity. If the third reading is a little lower, the yeasties are still chewing away, finishing their work; check again in another two or three days, etc, until the readings are the same.

Find an alcohol by volume calculator on the web, and punch in your original and final gravity readings to get your ABV.

Don't worry about the priming sugar; you'd have to massively, massively over-prime your beer to move your ABV a noticeable amount, and in that case, you'd be too busy ducking shrapnel from bottle-bombs to worry about your ABV anyway.
 
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lovebrewin

lovebrewin

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feinbera said:
and in that case, you'd be too busy ducking shrapnel from bottle-bombs to worry about your ABV anyway.

Hahaha
Thanks fellas that's cleared it up for me!!
 
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