In the United States, a blood alcohol concentration (BAC) of 0.08% is the legal threshold for intoxication in most states. That’s the level at which you can be charged with driving under the influence. But impairment starts well before that number, and how “drunk” you feel depends on factors that no single legal limit can capture.
The Legal Line: 0.08% BAC
Most U.S. states set the legal limit for driving at 0.08% BAC, meaning 0.08 grams of alcohol per deciliter of blood. Utah is a notable exception at 0.05%. Commercial drivers face a stricter limit of 0.04% nationwide. These numbers are not meant to define the point where impairment begins. They’re the point where lawmakers decided the risk to public safety is too high to allow someone behind the wheel.
Other countries draw the line differently. England, Wales, and Northern Ireland match the U.S. standard at roughly 0.08%. Scotland and Australia set it lower at 0.05%. Several European and Asian countries use 0.02% or have zero-tolerance policies. The variation reflects different cultural and policy judgments, not different biology.
What Each BAC Level Actually Feels Like
Your body doesn’t wait for 0.08% to start changing. Impairment is a sliding scale, and it begins with your first drink.
At 0.02%, roughly one drink for most people, you’ll feel slight warmth, mild relaxation, and a subtle mood shift. Your ability to track moving objects and divide your attention between two tasks is already declining, even though you likely feel completely fine.
At 0.05%, behavior becomes more exaggerated. Judgment is noticeably impaired, alertness drops, and coordination starts to slip. You may have trouble focusing your eyes. Most people feel good at this level, which is part of what makes it deceptive. This is where many countries set the legal driving limit.
At 0.08%, the U.S. legal threshold, muscle coordination is clearly affected. Balance, speech, vision, and reaction time all suffer. You’ll have trouble detecting danger, and short-term memory starts to falter. Reasoning and self-control are impaired. This is the point most people would describe as noticeably drunk.
At 0.15%, you’ve lost significant muscle control and balance. Vomiting is common unless you’ve built up a high tolerance or reached this level very slowly. Walking without stumbling is difficult.
At 0.30% to 0.40%, you’re in alcohol poisoning territory. Loss of consciousness is likely, and the situation is potentially life-threatening. Above 0.40%, the risk of coma and death from respiratory failure is severe.
How Many Drinks Does It Take?
A standard drink in the U.S. contains about 14 grams of pure alcohol. That translates to a 12-ounce beer at 5% alcohol, a 5-ounce glass of wine at 12%, or a 1.5-ounce shot of liquor at 40%. Many real-world pours exceed these sizes. A typical restaurant wine glass holds 6 to 8 ounces, and craft beers often run 7% to 10% alcohol, meaning one glass can count as nearly two standard drinks.
The National Institute on Alcohol Abuse and Alcoholism defines binge drinking as the pattern that brings BAC to 0.08% or higher. For a typical adult, that’s about five drinks for men or four drinks for women consumed in roughly two hours. For teenagers, it takes fewer: as few as three drinks for girls and three to five for boys, depending on age and size. High-intensity drinking, defined as double those thresholds (10 or more drinks for men, 8 or more for women in one occasion), carries sharply elevated risk of poisoning and injury.
Why the Same Number of Drinks Hits People Differently
Two people can drink the same amount and reach very different BAC levels. Body size and weight are the most obvious factors: a larger person has more blood volume to dilute the alcohol. But body composition matters just as much. Fat tissue doesn’t absorb alcohol the way water and muscle do, so someone with a higher body fat percentage will concentrate more alcohol in their bloodstream per drink.
Biological sex plays a significant role. Women generally absorb more alcohol and take longer to process it than men, even at the same body weight. This is largely because women tend to have proportionally less body water and more body fat, along with lower levels of the stomach enzyme that breaks down alcohol before it enters the bloodstream. The result is a higher BAC from the same number of drinks.
Whether you’ve eaten recently also matters. Food in your stomach slows the rate at which alcohol passes into your small intestine, where most absorption happens. Drinking on an empty stomach lets alcohol enter your blood much faster, producing a sharper spike in BAC.
Your Body Clears Alcohol Slowly
The average person eliminates alcohol at a rate of about 0.015% BAC per hour. That rate is relatively fixed. It doesn’t speed up with coffee, cold showers, or food after drinking. If you reach a BAC of 0.08%, it will take roughly five to six hours for your body to return to zero, assuming you stop drinking entirely. At 0.15%, you’re looking at ten hours. This is why people can still be legally impaired the morning after a heavy night of drinking.
Individual variation exists. Some people metabolize alcohol slightly faster or slower, with rates ranging from about 0.01% to 0.02% per hour. Chronic heavy drinkers sometimes develop faster elimination rates, but this doesn’t protect them from impairment or organ damage.
Feeling Sober Doesn’t Mean You Are
One of the most important findings in alcohol research is that how drunk you feel is a poor indicator of how impaired you actually are. Studies have found that people’s subjective sense of intoxication peaks about 24 minutes before their BAC peaks. In practical terms, this means you may start to feel like you’re “sobering up” while your blood alcohol is still climbing.
Research from Liberty University found that perceived intoxication correlated with behavioral impairment, but actual BAC did not always track with self-assessment. During and immediately after a drinking session, people were particularly bad at estimating their real level of impairment. In field data collected at fraternity parties, there was almost no relationship between how drunk people thought they were and their measured BAC. The takeaway is straightforward: your own sense of how impaired you are is unreliable, especially in the moment.
Tolerance makes this worse. Regular drinkers often feel functional at BAC levels that would leave an occasional drinker visibly intoxicated. But feeling functional is not the same as being unimpaired. Reaction time, judgment, and coordination are still degraded at the same BAC regardless of how accustomed you are to the sensation of being drunk. The legal system doesn’t care whether you feel fine. The 0.08% limit applies the same way to someone who drinks daily and someone who drinks once a year.