How can I tell the ABV% with a normal hydrometer?

Question

I have regular hydrometers to tell the specific gravity, anyone know what specific gravity converts to in ABV%?

Answer 1

Assuming you are making a fermented alcoholic beverage, any beer or winemaking site can give you the formula. You will need to know the specific gravity before and after fermentation. You will also need to know the temperature of the fluid and the temperature correction from your hydrometer.

If this is not a fermentation type question, you can work with the specific gravities of the two nonreacting miscible fluids - knowing that it will be the combination of the two - If you had a mixture that was 95% a fluid that had a specific gravity of 1.00 and 5% a fluid with a specific gravity of 0.79, you would end up with a fluid of specific gravity 0.95*1.00+0.05*0.79=0.990

The sugar in fermented beverages makes it generally harder than this, unfortunately....