BAC: How Alcohol Affects Your Body by the Numbers
Understand blood alcohol content, how it's calculated, and what different BAC levels mean for impairment.
Blood Alcohol Content (BAC) measures the percentage of alcohol in your bloodstream. At 0.08%, you are legally impaired in all 50 US states. But impairment begins well before that threshold — reaction time, judgment, and coordination are affected at BAC levels as low as 0.02%.
Our BAC Calculator uses the Widmark formula to estimate your BAC based on drinks consumed, body weight, gender, and time elapsed.
What the Numbers Mean
At 0.02-0.03% you feel relaxed. At 0.05% inhibitions lower and judgment begins to decline. At 0.08% (legal limit) coordination and reaction time are significantly impaired. At 0.15% you may vomit and have major balance issues. Above 0.30% is life-threatening.
Factors That Affect BAC
Gender matters — women typically have less body water and more body fat, so alcohol concentrates more. Weight matters — heavier people dilute alcohol across more body mass. Food slows absorption. Time is the only thing that lowers BAC, at approximately 0.015% per hour.
If alcohol is a regular part of your life, be aware of its caloric impact. Alcohol has 7 calories per gram — nearly as much as fat. Factor this into your daily calorie targets and TDEE.
Try the Calculator
Put these concepts into practice with our free BAC Calculator. No signup required.