Myth or fact

Your body clears one drink an hour

Short answerNo

By GyroscopeUpdated November 14, 20266 sources

No. Most adults take about 2 to 3.5 hours to clear one US drink, about twice what the rule says. Drink one an hour and the drinks stack up, so the level keeps climbing all evening and lasts well into the night.

Why does everyone believe it?

The rule is everywhere, and it’s easy to remember. It also matches what a drink feels like. The buzz from one drink fades in about an hour, so it seems as if the drink is gone. The alcohol in your blood doesn’t follow the feeling.

For the biggest bodies with the fastest livers, the rule is only off by about half an hour. But a US standard drink is 14 g of alcohol, and most bodies take a good deal longer than an hour to clear that much.

What does the liver really do?

Think of your liver as a store with one checkout lane. Once a drink or two is in, the lane is busy, and the line moves at the same pace no matter how many people join it. Order a new drink every hour and the line just gets longer.

The cashier is an enzyme, alcohol dehydrogenase, which fills up after the first drink or two. A 2010 review of the published research found that from then on, the level in your blood falls by a fixed amount each hour, about 15 mg per 100 mL on average, 10 to 15 on an empty stomach and 15 to 20 after a meal.

One US drink raises a 130 lb woman’s level by close to three hours of clearing at the average pace, because alcohol spreads through body water, and pound for pound women have less of it. It raises a 190 lb man’s by about an hour and a half. The last bit clears more slowly, because the enzyme slows down once there’s very little left. On our engine, with an average liver, that adds up to these times from the first sip until it’s mostly cleared.

Even the biggest body here, with a liver at the fast end of normal, takes about an hour and a half for one drink.

What happens at one drink an hour?

The drinks pile up. Say someone has four US drinks, at 7, 8, 9 and 10pm. By the one-an-hour rule, they’d be clear at 11pm. On our engine, with food not known, here’s when each body is mostly clear.

For a lot of people, four drinks that “should” be gone by bedtime are still in their blood at breakfast. In the WHOOP data on 20,968 members, people typically finished their last drink about 3 to 3.5 hours before bed, which is enough for one drink in most bodies and not enough for two or three.

Why do some people clear faster?

The full range runs from 10 to 35 mg per 100 mL an hour, according to the 2010 review. The fastest rates in it, 25 to 35, came from people in alcohol detox, whose livers had built up a second clearing enzyme after long stretches of heavy drinking. Food helps a little too, which is why the rate is higher after a meal.

Body water varies from person to person. The number forensic scientists use for it changes with sex and build, from about 0.80 in a very lean man down to 0.53 to 0.60 in a heavier woman, depending on the method, according to a 2015 review. That review says any calculated level should come with a range, which is why every time on this site has one.

The best case for the rule

“It’s a simple rule that keeps people from drinking too fast.” It does push people to slow down, which helps. But it sets the wrong expectation for how long a drink lasts, and it tells people they’re clear when they aren’t. NIAAA also points out that your level can keep rising after your last drink, because alcohol still in the stomach and gut keeps entering the blood. Nobody should use the one-an-hour rule, or any calculator, to decide whether they can drive. Don’t drive after drinking.

See it on your own drinks

The blood curve calculator draws your evening with the one-drink-an-hour line beside it, so you can see the gap. Last call works backward from your bedtime, and How your body clears alcohol has the full science.