Most alcohol research tends to assume that drinks contain the same amount of pure alcohol: 0.6 ounces or 18 milliliters. Why is this important? Researchers need accuracy to do their job well, and consumers need to know what they’re drinking, especially if they are going to drive. New research has found that the average size of wine, mixed drinks and beer served in Northern California bars, restaurants and other drinking establishments is larger than the standard, and alcohol content can vary widely. Researchers visited 80 bars and restaurants in Northern California.