A blood alcohol concentration (BAC) of 0.18 is very high. It is more than twice the legal driving limit of 0.08 in every U.S. state, and it falls into a range where disorientation, loss of coordination, and blackouts are common. At this level, your brain’s ability to form new memories and control your body is significantly impaired.
What 0.18 BAC Feels Like
At a BAC between 0.18 and 0.30, most people appear visibly disoriented. The part of your brain responsible for coordination is heavily affected, which means you may struggle to walk or stand without help. Speech is typically slurred, reaction time is drastically slowed, and judgment is poor enough that you may not realize how impaired you are.
Blackouts are likely at this level. A blackout isn’t the same as passing out. You may still be conscious, talking, and moving around, but your brain stops recording new memories. The next day, you have gaps or complete blanks for hours of the night. This happens because the memory-forming region of the brain essentially shuts down under this much alcohol. Some people experience “brownouts,” where memories are fragmented rather than completely absent, but full blackouts are common at 0.18.
How Many Drinks It Takes
Reaching a 0.18 BAC takes a significant amount of alcohol, though the exact number of drinks depends on your body weight, sex, how fast you drank, and whether you ate. One standard drink equals 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof liquor.
For a rough idea: a 120-pound man could reach 0.18 with about 4 drinks, while a 200-pound man would need around 7 drinks. Women generally reach higher BAC levels with fewer drinks due to differences in body composition and metabolism. A 120-pound woman could reach this range with about 6 drinks, while a 200-pound woman might need around 10. These are estimates for drinks consumed within a short window. Drinking over many hours with food will produce lower peaks.
How It Compares to Legal Limits
The standard legal limit for driving in the U.S. is 0.08 BAC. A level of 0.18 is 2.25 times that threshold, which matters legally because many states impose enhanced penalties at higher BAC levels. Arizona, for example, classifies any BAC of 0.15 to 0.19 as an “extreme DUI,” carrying harsher mandatory sentences than a standard DUI. A BAC of 0.20 or above qualifies as a “super extreme DUI” with even steeper consequences. Many other states have similar tiered systems, with the enhanced threshold typically falling between 0.15 and 0.17.
At 0.18, you would face the most serious category of DUI charges in a number of states, not just a standard offense. Penalties often include longer license suspensions, mandatory jail time, higher fines, and required ignition interlock devices on your vehicle.
How Far 0.18 Is From Dangerous Territory
While 0.18 is not immediately life-threatening for most people, it sits uncomfortably close to levels where medical emergencies begin. Alcohol poisoning, which can involve vomiting while unconscious, dangerously slow breathing, and loss of consciousness, typically occurs in the 0.30 to 0.40 range. A BAC above 0.40 carries a risk of coma and death from respiratory failure.
That said, 0.18 is not “safe” just because it’s below the poisoning threshold. The risk of falls, accidents, choking on vomit, and dangerous decisions is already very real at this level. Individual tolerance also varies widely. Someone who rarely drinks may experience far more severe effects at 0.18 than a heavy drinker would, even though the physical damage to the brain and body is happening regardless of how impaired someone feels.
How Long 0.18 Takes to Wear Off
Your liver processes alcohol at a relatively fixed rate: roughly 0.015 to 0.020 BAC per hour. No amount of coffee, food, water, or sleep speeds this up. Starting from 0.18 and metabolizing at the average rate of about 0.015 per hour, it would take approximately 12 hours to reach 0.00. Even at the faster end of 0.020 per hour, you’re looking at 9 hours.
This means if you stop drinking at midnight with a BAC of 0.18, you could still be above the legal driving limit well into the following morning. Many people are surprised to learn they’re still legally impaired at 8 or 9 a.m. the next day. You will also likely feel significant hangover effects for hours after your BAC returns to zero, since the inflammatory and dehydrating effects of that much alcohol linger after the alcohol itself is gone.