Here is a comparison of beers, wines and spirits volume of pure alcohol basted on what is known
as a "standard serving" of each. Look at it like this a 12 oz. cocktail with 1.5 oz. of 80 proof spirits has about 0.6 oz. of pure alcohol, and a 12 oz. beer which is rated at 5% (10 proof) alcohol also contains 0.6 oz. of pure alcohol. Below is a chart that shows how much alcohol there is in a "standard serving" of alcoholic beverages.