what is the standard drinking size in ounces for 80-proof liquor?

The standard drinking size for 80-proof liquor is 1.5 ounces. This is considered one standard drink of liquor, which contains about 40% alcohol by volume. This applies to common distilled spirits such as whiskey, vodka, gin, tequila, brandy, and cognac. So, if you are pouring an 80-proof liquor, a standard serving size is 1.5 oz. Mixed drinks may contain more than one standard drink depending on how much liquor they include. This standard serving size of 1.5 ounces helps in tracking alcohol intake and estimating blood alcohol content responsibly. The consensus across multiple sources is that 80-proof liquor has a standard drink size of 1.5 ounces.