A BAC Calculator is a tool used to estimate a person's Blood Alcohol Concentration (BAC) based on various factors. It typically requires information such as the number of drinks consumed, the time period over which they were consumed, the person's weight, and gender. This helps individuals understand how alcohol affects their body and whether they are above the legal limit for driving. Using a BAC Calculator can promote responsible drinking by providing an estimate of impairment levels. However, it is important to note that these calculators are not always accurate, as individual metabolism and other factors can influence BAC levels differently for each person.