How do I measure how much alcohol is in my wine?
You will need to take a hydrometer reading of the grape juice before you add the yeast (this is called the Original Gravity (OG)), then a hydrometer reading once it had finished fermenting at the bottling stage (this is called the Final Gravity (FG)). From these 2 readings you can work out the alcohol content of your wine using a simple calculation.
OG - FG = a
FG / 0.794 = b
1.775 - OG = c
a * 76.08 = d
d / c = y
y * b = % ABV
How do I measure how much alcohol is in my wine if I have not taken hydrometer readings?
There is a device called a Vinometer. It is a very thin glass tube. You fill it up until wine drips from the bottom.
Then turn it over and the wine will drain from the thin tube.
Where the wine stops is the ABV of the wine.
This is only an estimate and 3 measures should be taken and the average of the 3 will give you a more accurate reading.
However, if it has not fully fermented, is not perfectly clear, or has had sugar added, this will not give an accurate reading.
Are there any other ways to measure how much alcohol is in my wine?
You can send a sample of your wine away for laboratory testing.
This is very costly, but will give you an exact measure of the alcohol content.