How to calculate FG after adding sugar to secondary fermentation?

[CV_Apple_Gal]

Hi all,

I started with a gallon of cider that I wanted to turn into wine, (which actually turned out quite successfully, if you like dry whites)

OG: 1059
SG when racked into secondary: .998
Sugar added, then SG was 1020
FG when bottled a month later: .999

Is there any way to calculate what my ABV is, having added sugar midway?

Thanks!

 

[Ty520]

just add up the total change: (1059-998= 61 points or 8%) + (1020-999 = 21 points or 2.76%) = 10.76% ABV

 

[Chalkyt]

As above.

However, there is a simple formula to calculate ABV from SG change with reasonable accuracy.

It is ABV% =130 x (OG-FG)

FYI attached is a paper about this which also covers calculating ABV from first principles (i.e. the amount of sugar fermented)