Alcohol by volume. Measurement of the percent of ethyl alcohol present in a volume of liquid. This is calculated by taking the original gravity (sugar content) and subtracting the final gravity. That sum is multiplied by 131.25.  1% ABV in a 5 gallon batch of beer is equal roughly 1LB of fermentable sugar. ABV is about 25% more than ABW (Alcohol by Weight).  ABV is commonly used as the standard measure of alcohol in beer and what most consumers are used to.