To measure the ABV in your spirit, you will need an alcoholmeter.
This is a small float, with a scale in it. The more alcohol that is present, the lighter the density of the liquid and so the alcoholmeter sinks a bit lower. You then read off the scale how much alcohol is present and dilute accordingly.
If the alcoholmeter isn't showing any alcohol - The alcoholmeter works based on the density of the liquid. When we make liqueurs, we add bases which alter the density of the liqueur. This means that now after the base has been added that the alcoholmeter cannot be used to measure the ABV as the density of the liqueur is now not the alcohol alone but has also been affected by the base. It is designed to only measure the ABV of the spirit.
If you do not have access to an alcoholmeter, see below.
Steps to calculate the final ABV of a made-up spirit or liqueur based on any given recipe.
Step 1 is to determine how much alcohol is required in the recipe (we need to determine this before calculating the final ABV of the made-up liqueur). Some flavourings will have this clearly stated in the recipe whereas others won't, but will rather say top up with alcohol to the finished beverage volume or something along those lines. If the latter is the case, please see below:
- Volume of alcohol in recipe = Final finished beverage volume - flavouring volume - water volume
Example - Rhubarb and Ginger Gin Icon Liqueur:
Volume of alcohol in recipe = 1000 ml - 330 ml - 170ml
Volume of alcohol in recipe = 500 ml
Step 2 is to actually calculate what the final ABV of the made-up liqueur will be. The general formula is as below:
- % ABV of made-up liqueur or spirit = % ABV of alcohol called for in recipe X ( volume of alcohol in recipe / final finished beverage volume)
Note: The 'volume of alcohol in recipe' is calculated using step 1 if it isn't clearly stated on the flavouring instructions. All instructions will state the '% ABV of alcohol called for in recipe'
Example - Rhubarb and Ginger Gin Icon Liqueur:
% ABV of made up liqueur or spirit = 40% X (500/1000)
% ABV of made up liqueur or spirit = 20% ABV