However, these calculators have limitations that make it unsafe to rely on them. For instance:
- The majority of BAC calculators have predefined values for both alcohol serving size and alcohol content. For instance, a beer is 12oz and 4.5% alcohol content, a glass of wine is 4oz and 15% alcohol content and a shot is 1.5oz and 40% alcohol content. If you're consuming a drink with a larger serving size and/or one that’s stronger than average, the calculator will underestimate your BAC.
- BAC calculators do not take into account the amount of food in your stomach. A person’s BAC rises faster when they consume alcohol on an empty stomach since there’s no food to dilute the alcohol.
- BAC calculators assume your alcohol consumption is consistent over a specified period of time. For instance, when you drink two drinks in two hours, the calculator assumes you have consumed one drink per hour. If drinks are consumed more quickly, your estimated BAC will be miscalculated.
- BAC calculators use a formula based on average values – the average amount of water in the body and in the blood, and the average metabolism rate. Individual factors that affect these values and are not calculated in a BAC estimate.
- On the other hand, a breathalyzer will provide a much more accurate estimate of a person’s BAC because they provide values based on a person’s deep lung breath sample. (All the more reason to shop for a BACtrack breathalyzer now!).