One standard drink in the United States contains 0.6 ounces (14 grams) of pure alcohol. That’s the fixed amount health agencies use as a reference point, regardless of what type of beverage you’re drinking. The glass size changes depending on the drink, but the alcohol inside stays the same.
What Counts as One Standard Drink
Because different beverages have different alcohol concentrations, the serving size that equals one standard drink varies. A regular beer at about 5% alcohol by volume (ABV) counts as one standard drink at 12 ounces, roughly the size of a typical can or bottle. A glass of wine at about 12% ABV counts as one standard drink at 5 ounces, which is noticeably smaller than many people pour at home. A shot of distilled spirits (vodka, whiskey, rum, tequila) at 40% ABV, also labeled as 80-proof, counts as one standard drink at 1.5 ounces.
All three of those servings deliver the same 14 grams of pure alcohol to your body. The container looks different, but your liver processes the same amount.
Why Your Actual Drink May Not Equal “One Drink”
The standard drink definition assumes specific ABV percentages that don’t always match what’s in your glass. A craft IPA at 7% to 9% ABV in a standard 12-ounce can contains significantly more alcohol than a 5% lager. A 12-ounce pour of a 9% beer holds roughly 1.8 standard drinks, not one. Similarly, a generous wine pour of 8 ounces at a restaurant is closer to 1.5 standard drinks than a single one.
Cocktails are especially tricky. A margarita or Long Island iced tea can contain two, three, or even four standard drinks depending on the recipe. A pint glass of a strong craft beer at a brewery is 16 ounces, not 12, which bumps even a 5% beer up to about 1.3 standard drinks.
You can estimate the alcohol in any drink with a simple formula: multiply the volume in ounces by the ABV (as a decimal), then divide by 0.6. For example, a 16-ounce pint of 6% beer: 16 × 0.06 = 0.96 ounces of pure alcohol, divided by 0.6 = 1.6 standard drinks.
How Your Body Processes One Drink
Your liver breaks down alcohol at a remarkably steady pace: roughly one standard drink per hour. This rate doesn’t speed up with coffee, food, water, or cold showers. Time is the only thing that clears alcohol from your system.
For a person of average build, one standard drink raises blood alcohol concentration (BAC) by approximately 0.01% to 0.03% over an hour. That range depends on body weight, sex, how recently you ate, and individual metabolism. Women generally reach a higher BAC than men from the same amount of alcohol, partly because of differences in body water content and enzyme activity.
If you drink faster than one drink per hour, alcohol accumulates in your bloodstream because your liver can’t keep up. Two drinks in an hour doesn’t mean you’ll be back to zero in two hours either. The math stacks: your liver is still working through the backlog while new alcohol enters your system.
Standard Drinks Vary by Country
There is no single international definition of a standard drink. The U.S. sets it at 14 grams of pure ethanol. Canada defines a standard drink as containing about 17 milliliters of pure ethanol (roughly 13.6 grams). The UK uses “units” of 8 grams each, and Australia defines a standard drink as 10 grams. This means health guidelines from different countries aren’t directly comparable unless you convert to the same measurement.
If you’re reading drinking guidelines from a non-U.S. source, pay attention to which standard is being used. A recommendation of “no more than two standard drinks” means very different total amounts of alcohol depending on which country’s definition applies.
What “Moderate Drinking” Means in Standard Drinks
U.S. guidelines define moderate alcohol use as two drinks or fewer per day for men and one drink or fewer per day for women. These limits are based on the 14-gram standard drink, so they assume the specific serving sizes listed above: 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of spirits.
Pouring a large glass of wine and calling it “one drink” doesn’t align with these guidelines if the actual pour is 8 or 10 ounces. The same goes for ordering a double at a bar. Knowing the actual alcohol content of what you’re drinking makes these guidelines practical rather than abstract. A single cocktail can put you at or past the moderate threshold before you’ve finished it.