Blood Alcohol Content (BAC): How Your Body Processes Alcohol

Blood alcohol content (BAC) is a percentage that measures the concentration of alcohol in your bloodstream. A BAC of 0.08% — the legal driving limit in most US states — means your blood contains 0.08 grams of alcohol per 100 milliliters. Understanding how BAC works can help you make safer decisions around alcohol consumption.

What affects your BAC

The main factors are: how much you drank, your body weight, your sex (women generally reach higher BAC at equivalent doses due to lower body water percentage), whether you ate beforehand, and how fast you drank. The type of alcohol matters only insofar as its strength determines how much ethanol is in each drink.

How your body eliminates alcohol

The liver metabolizes alcohol at a roughly fixed rate — about one standard drink per hour for most adults. This rate cannot be sped up by coffee, food, or water after drinking. Our BAC calculator models this elimination curve so you can estimate when you will return to zero after a given amount of drinks.

What different BAC levels feel like

At 0.02–0.05%, most people feel relaxed and mildly impaired. At 0.06–0.10%, judgment and coordination are notably impaired. At 0.11–0.20%, significant impairment including slurred speech and stumbling. Above 0.25%, loss of consciousness and dangerous respiratory depression can occur. Effects vary significantly by individual tolerance.