"R-D-C" Royal De-Canter? wrote (in part):
I started with SG 1.092 giving PA of 12.5%.
Finished at 0.984.
So, do I have a 12.5% abv wine or do I use the total drop
of SG giving 14.5%?

William Frazier wrote:
You have about 12.1% v/v alcohol.

Please explain the 12.1% computation.
Dick

Dick - This has been discussed a lot recently. Here's the formula I use;
Reference: Homebrewing, Volume 1 by Al Korzonas
Page 31

Calculation of alcohol by weight;
% ABW = (OG - FG) x 105

Calculation of alcohol by volume;
% ABV = ABW x 1.25

Combined method for alcohol by volume;
% ABV = (OG - FG) x 131.25


OG refers to original specific gravity. FG refers to final gravity or the
specific gravity when fermentation is complete. It's my belief that you
can't ferment more sugar than is in the wine to begin with. So, the FG
should be considered 1.000. The fact that we observe specific gravities
less than 1.000 is because of the presence of alcohol and the way it effects
the hydrometer. Therefore, when I calculate alcohol content I always use a
FG of 1.000.

In R-D-C's case;
%ABW = (1.092-1.000) x 105 or 9.66%
%ABV = 9.66 x 1.25 = 12.075 or 12.1%

Bill Frazier
Olathe, Kansas USA