vodka that is marked as 80 proof has 40% abv. this means that 12 oz (354ml) of 5% beer contains 0.6 oz (17.7ml) pure alcohol. the vodka shot at 1.5 oz (44ml) has 0.6 oz (17.4ml) of alcohol. when you compare alcohol content, this fairly simple math shows that one regular beer is equal to one shot.