You’re technically drunk when alcohol impairs your judgment, coordination, and reaction time, which starts happening at lower levels than most people expect. In the United States, a blood alcohol concentration (BAC) of 0.08% is the legal threshold for intoxication while driving, but measurable impairment begins well before that, at around 0.02% to 0.05%. How quickly you reach those levels depends on your body size, biological sex, how much you’ve eaten, and your genetics.
What Happens at Each BAC Level
Blood alcohol concentration is expressed as a percentage of alcohol in your bloodstream. Even small increases produce noticeable changes in how you think and move.
- 0.02%: Mood shifts slightly. You feel more relaxed, and your judgment is subtly off. Most people wouldn’t call this “drunk,” but the brain is already being affected.
- 0.05%: You feel uninhibited, your alertness drops, and your judgment is clearly impaired. This is the level many countries use as a legal limit.
- 0.08%: Muscle coordination is reduced, it’s harder to detect danger, and reasoning slows down. This is the U.S. legal limit for driving.
- 0.10%: Reaction time drops noticeably. Speech starts to slur and thinking feels sluggish.
- 0.15%: Nausea, vomiting, and loss of balance set in. Mood swings become more extreme and muscle control deteriorates.
- 0.15% to 0.30%: Confusion, drowsiness, and repeated vomiting. This range is dangerous.
- 0.30% and above: Risk of alcohol poisoning, loss of consciousness, coma, and death from breathing failure.
The important takeaway is that “drunk” isn’t a single on/off switch. Your brain begins losing function at the very first level, and the effects stack as your BAC climbs.
Why Alcohol Slows Your Brain Down
Alcohol works on two systems in the brain simultaneously. It boosts the activity of your brain’s main braking system (a chemical called GABA that quiets nerve signals) while suppressing the main accelerator (glutamate, which excites nerve signals). The result is a brain that’s running slower across the board: slower processing, slower reactions, looser inhibitions. This is why alcohol is classified as a depressant, not because it makes you sad, but because it depresses brain activity.
The first areas affected tend to be the ones responsible for judgment and impulse control, which is why you feel confident and social early on. Motor coordination and balance are suppressed next. At very high levels, the parts of the brain controlling breathing, heart rate, and body temperature start to shut down.
How Fast You Get Drunk Varies Widely
Two people can drink the same amount and reach very different BAC levels. The biggest factors are body size and composition: a smaller person reaches a higher BAC faster because there’s less body water to dilute the alcohol. Women generally reach higher BAC levels than men after the same number of drinks, partly due to differences in body water percentage and partly because women produce less of the enzyme (alcohol dehydrogenase) that begins breaking down alcohol in the stomach.
Food makes a significant difference. Eating before or while drinking slows the rate at which alcohol passes into your small intestine, where most absorption happens. Drinking on an empty stomach can cause your BAC to spike much faster. Carbonated drinks like champagne or mixed drinks with soda can also speed absorption.
Genetics play a role too. Your body breaks alcohol down in two steps, first converting it into a toxic byproduct called acetaldehyde, then converting that into harmless acetate. Variations in the enzymes that handle these steps differ across individuals and populations. Some people process alcohol quickly and feel fewer effects per drink. Others accumulate acetaldehyde faster, leading to flushing, nausea, and a generally worse experience.
What Counts as One Drink
People often underestimate how much they’re actually consuming because glass sizes and alcohol content vary so much. A standard drink in the U.S. contains roughly the same amount of pure alcohol regardless of the beverage type:
- Beer: 12 ounces at 5% ABV
- Wine: 5 ounces at 12% ABV
- Liquor: 1.5 ounces (one shot) at 40% ABV
- Malt liquor: 8 ounces at 7% ABV
A large pour of wine at a restaurant is often 8 to 9 ounces, nearly two standard drinks. A craft IPA at 8% ABV in a pint glass is closer to 1.5 standard drinks. Cocktails with multiple shots can contain two or three standard drinks in a single glass. If you’re trying to track your intake, these hidden extras matter.
Feeling Sober Doesn’t Mean You Are
One of the most dangerous aspects of alcohol is the gap between how impaired you feel and how impaired you actually are. A systematic review of studies measuring both subjective and objective impairment found that people who drink more frequently tend to underestimate how affected they are. In other words, tolerance changes how drunk you feel without fully protecting you from the cognitive and motor deficits that come with a given BAC. You may feel perfectly capable of driving while your reaction time and judgment are measurably worse.
This disconnect is strongest in the 0.05% to 0.08% range, where many people feel “fine” or just “a little buzzed” but already have impaired coordination, slower reflexes, and worse judgment than they realize. Tolerance built from regular drinking lets you function more normally at a given BAC, but it doesn’t eliminate the underlying impairment.
How Long It Takes to Sober Up
Your liver processes alcohol at a fairly fixed rate: about 0.015 to 0.020 percentage points of BAC per hour. That means if you’re at the legal limit of 0.08%, it takes roughly four to five hours to reach 0.00%. Nothing speeds this up meaningfully. Coffee, cold showers, and food may make you feel more alert, but they don’t change how fast your liver clears alcohol from your blood.
This is worth doing the math on. If you stop drinking at midnight with a BAC of 0.12%, you likely won’t be at zero until around 6 to 8 a.m. Many people are still legally impaired the morning after a night of heavy drinking without realizing it.
Signs of Alcohol Poisoning
At BAC levels above 0.30%, the risk of alcohol poisoning becomes serious. The warning signs include mental confusion or stupor, inability to stay conscious or be woken up, vomiting (especially while unconscious), seizures, breathing slower than eight breaths per minute, gaps of ten seconds or more between breaths, clammy skin, bluish skin color, and extremely low body temperature. Loss of the gag reflex is particularly dangerous because it means a person can choke on their own vomit without waking up.
Alcohol poisoning is a medical emergency. The brain areas controlling breathing and heart rate are being suppressed, and without intervention, the outcome can be fatal.