This tool calculates a person's blood alcohol content, or "BAC" for short. As you can see below, BAC is calculated from beverages consumed -- quantity in ounces, percentage of alcohol, time spent in consumption -- and body weight.
As a general guide, for fluid ounces you can enter 12 for beer, 4 for a wine glass, and 1.5 for one shot. For the percentage of alcohol, you can enter 4-4.5% for beer, 15-20% for wine, and 30-50% for one shot (don't include the percent sign).