Alcohol Determination By Specific Gravity -

• This method provides an approximation of the alcohol content only.

• The method assumes that the difference in Specific Gravity before and after fermentation is due solely to the conversion of sugars before fermentation into alcohol after fermentation.

• The method relies on -

• all the wines measured, starting with the same sugar levels

• all the sugars being fermented, with the wine finishing dry

• the unfermentable sugars being the same for all wines

• Keeping the above in mind -

%v/v alcohol = (SG2 - SG1) / 0.0074

Where -

SG1 is the initial specific gravity measurement

SG2 is the final specific gravity measurement.

G30. HOW TO MEASURE ALCOHOL LEVELS IN YOUR WINE To calculate Alcohol by Volume: Subtract the last reading from the initial gravity and divide the result by 0.0074. This gives the approximate alcohol content in %. Ex.: S.G. = 1.070 F.G. = 0.995 1.070 - 0.995 = 0.075 0.075 / 0.0074 = 10.15% It does not matter what the first or last reading is, both mean little alone. The difference between the two does! Usually there is also an alcohol scale marked directly on a hydrometer; subtract initial potential alcohol reading from final, and the difference is the approximate alcohol content. Using the Brix scale, 1 degree Bx = 1 g/100 ml, or 10 g/liter. When you read a Bx of say 22, divide the 22 by 2 to get 11, and add 1, for a final alcohol of 12%. It is an extremely good rule of thumb.