In the United States, a blood alcohol concentration (BAC) of 0.08% is the legal threshold for drunk driving in every state except Utah, which sets the limit at 0.05%. But “drunk” as a feeling starts well before that. Most people notice impaired judgment, slower reflexes, and reduced coordination beginning around 0.05% to 0.06% BAC, and the effects escalate sharply from there.
BAC is expressed as a percentage of alcohol in your bloodstream by weight. A BAC of 0.08% means 0.08 grams of alcohol per 100 milliliters of blood. That number sounds tiny, but your brain is remarkably sensitive to alcohol, and small increases produce large changes in how you think, move, and react.
What Each BAC Level Feels Like
At 0.02% to 0.03%, roughly one drink for most people, you’ll feel mildly relaxed. Your mood lifts slightly and your inhibitions loosen, but you probably wouldn’t describe yourself as drunk. Reaction time slows just enough to be measurable on a test, though you likely won’t notice it.
Between 0.05% and 0.06%, the effects become harder to ignore. Your coordination starts to slip, your judgment weakens, and you may talk louder or take social risks you normally wouldn’t. This is the range where many people would say they feel buzzed or tipsy. Utah’s 0.05% legal limit reflects research showing that crash risk rises meaningfully at this level.
At 0.08%, the legal limit in 49 states, you have clear impairment in muscle coordination, balance, reaction time, and reasoning. Speech may slur. Driving ability is significantly compromised, which is why this threshold exists. For many people, 0.08% is three to four drinks consumed within about two hours.
From 0.10% to 0.15%, motor control deteriorates noticeably. Walking becomes unsteady, speech is slurred, and your ability to process what’s happening around you slows. Most people at this level would be described as visibly drunk.
At 0.15% to 0.30%, you’re in dangerous territory. Vomiting, severe loss of balance, and blackouts (gaps in memory) are common. Your gag reflex may weaken, which creates a choking risk if you vomit while lying down.
Between 0.30% and 0.40%, alcohol poisoning is likely. Loss of consciousness, dangerously slow breathing, and a drop in body temperature can all occur. Above 0.40%, the risk of coma and death from respiratory failure is real and immediate.
How Many Drinks Get You There
A standard drink in the U.S. contains about 14 grams of pure alcohol. That equals 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 popular drinks exceed these sizes. A pint of craft IPA at 7% alcohol is closer to two standard drinks. A generous pour of wine at a restaurant can easily be 8 ounces, not 5.
Your body processes roughly one standard drink per hour. That rate is essentially fixed. Your liver cannot speed up no matter how much water you drink, how much coffee you have, or how badly you want to sober up. Time is the only thing that lowers your BAC. So if you drink three beers in an hour, your body only clears one drink’s worth of alcohol in that time, and the rest accumulates in your blood.
Why the Same Number of Drinks Hits People Differently
Body size is the most obvious factor. A larger person has more blood volume and body water to dilute the alcohol, so the same three drinks produce a lower BAC in someone who weighs 200 pounds than in someone who weighs 130. But weight alone doesn’t tell the whole story.
Body composition matters too. Muscle tissue absorbs alcohol, while fat does not. Two people at the same weight will reach different BAC levels if one carries more muscle and the other carries more fat. This is one reason alcohol tends to affect women more strongly than men at the same body weight. Women on average have a higher ratio of body fat to water, which concentrates alcohol in a smaller volume of fluid. Pharmacologists quantify this with a distribution constant: roughly 0.68 for an average man and 0.55 for an average woman, meaning women distribute alcohol into a smaller proportion of their body weight.
Food in your stomach makes a significant difference. Eating before or while drinking slows the rate at which alcohol passes into the small intestine, where most absorption happens. A valve at the bottom of the stomach closes during digestion, keeping alcohol in the stomach longer and giving your body more time to process it. Research from Johns Hopkins found that having food in your system increases the rate your body clears alcohol from the blood by 25% to 45%. Drinking on an empty stomach means alcohol hits your bloodstream faster and your peak BAC will be noticeably higher.
Several other factors play a role. Carbonated drinks (champagne, mixed drinks with soda) speed up absorption. Fatigue and stress can amplify intoxication. Drinking at high altitude can nearly double the felt effect for the first few days before your body adjusts. And mixing alcohol with medications or other drugs can intensify impairment unpredictably.
Tolerance Is Not the Same as Sobriety
Regular drinkers often develop tolerance, meaning the same amount of alcohol produces less noticeable intoxication over time. This is a real physiological adaptation, but it’s also misleading. Tolerance changes how drunk you feel, not how impaired you actually are. A person with high tolerance may appear sober to friends and even to themselves while their BAC is well above the legal limit. Their reaction time, coordination, and judgment are still compromised. Tolerance makes heavy drinking more dangerous, not less, because it masks the very signals your body uses to tell you to stop.
How BAC Is Measured
The two most common methods are breath testing and blood testing. A breathalyzer estimates your BAC by measuring alcohol vapor in your exhaled breath and converting it to a blood equivalent. It’s convenient and fast, which is why police use it roadside. However, breathalyzers are significantly less precise than blood draws. Various factors, including mouth alcohol from recent drinking or even mouthwash, body temperature, and device calibration, can skew the reading. Blood tests, taken at a hospital or station, measure alcohol directly in a blood sample and are considered the more reliable standard.
The Key Numbers to Remember
- 0.05%: Noticeable impairment begins for most people. Legal limit in Utah.
- 0.08%: Legal limit for driving in 49 states. Clear impairment in coordination, reaction time, and judgment.
- 0.15%: Severely impaired. Vomiting and blackouts become common.
- 0.30% to 0.40%: Alcohol poisoning territory. Loss of consciousness and life-threatening suppression of breathing.
- Above 0.40%: Risk of coma and death.
Your body clears about one standard drink per hour, and nothing speeds that up. If you’ve had four drinks in two hours and stop, it will still take roughly two more hours for your BAC to return to zero. Planning around that math is more reliable than trying to gauge how drunk you feel, since subjective feelings of intoxication don’t track neatly with actual impairment.