A standard drink in the United States contains about 14 grams of pure alcohol, which equals roughly 0.6 fluid ounces. That number stays the same whether you’re drinking beer, wine, or spirits. What changes is the size of the glass.
What Counts as One Standard Drink
Because different beverages have different alcohol concentrations, the serving size for one standard drink varies quite a bit:
- Beer (5% ABV): 12 ounces, a typical can or bottle
- Malt liquor (7% ABV): 8 ounces
- Wine (12% ABV): 5 ounces
- Distilled spirits (40% ABV, or 80-proof): 1.5 ounces, a single shot
Each of these pours delivers the same 14 grams of pure alcohol. The logic is straightforward: a stronger drink gets a smaller pour so the alcohol content stays constant. This is the definition used by both the NIAAA and the CDC, and it’s the basis for all U.S. dietary guidelines around alcohol.
How to Calculate Grams of Alcohol Yourself
If a drink doesn’t fit neatly into one of those categories, you can figure out the grams of pure alcohol with a simple formula. Multiply the volume in ounces by the ABV (as a decimal), then convert to milliliters, then adjust for alcohol’s density.
Here’s the step-by-step version: take the number of fluid ounces, multiply by the ABV percentage (for example, 0.05 for a 5% beer), then multiply by 29.6 (to convert ounces to milliliters), then multiply by 0.79 (because alcohol is lighter than water, weighing only 0.79 grams per milliliter instead of 1 gram).
For a standard 12-ounce, 5% beer: 12 × 0.05 × 29.6 × 0.79 = about 14 grams. The math confirms the standard.
Why Serving Size Alone Is Misleading
The biggest practical mistake people make is assuming that one glass, can, or bottle equals one standard drink. A 12-ounce bottle of 10% ABV craft beer contains 28 grams of alcohol, which is two standard drinks, not one. A generous restaurant pour of wine at 6 or 7 ounces pushes well past a single standard drink. A cocktail made with two ounces of spirits is already 1.3 standard drinks before you account for any liqueurs mixed in.
Craft beers are especially tricky. A 12-ounce IPA at 7% ABV contains about 19.5 grams of alcohol. At 9% ABV, that same 12-ounce pour hits roughly 25 grams, nearly double the standard. If you’re keeping count for health or safety reasons, the ABV on the label matters more than the size of the container.
How Your Body Processes 14 Grams
Your liver breaks down alcohol at a fairly fixed rate: roughly 7 grams per hour for an average-sized adult (about 154 pounds). That means one standard drink takes approximately two hours to fully metabolize. Drinking faster than that causes alcohol to accumulate in your bloodstream.
One standard drink typically raises blood alcohol concentration (BAC) by about 0.01 to 0.03 percent in an hour for a person of average build. That range depends on your weight, sex, body composition, whether you’ve eaten recently, and individual differences in liver enzyme activity. Smaller people and those with less muscle mass generally see a larger BAC increase from the same amount of alcohol.
How Other Countries Define a Standard Drink
The 14-gram standard is specific to the United States, and it’s not universal. The United Kingdom defines a unit of alcohol as 8 grams. Australia uses 10 grams. Many European countries use 10 or 12 grams. Japan’s standard is 19.75 grams. This means that international guidelines about “low-risk drinking” don’t translate directly across borders. Two drinks by the Australian definition is 20 grams, while two drinks by the U.S. definition is 28 grams.
If you’re reading health research from another country, check which standard they’re using. A study recommending “no more than two drinks per day” means something quite different depending on whether those drinks are 8-gram UK units or 14-gram U.S. standard drinks.
Putting the Numbers to Use
Knowing that a standard drink contains 14 grams of alcohol gives you a concrete way to track what you’re actually consuming. The U.S. Dietary Guidelines define moderate drinking as up to one standard drink per day for women and up to two for men, which translates to 14 grams and 28 grams respectively. Anything above that threshold increases health risks in a dose-dependent way: more grams, more risk.
The simplest way to apply this is to check the ABV on whatever you’re drinking and adjust your mental count. That 16-ounce pint of 6% beer at a bar isn’t one drink. It’s closer to 1.4 standard drinks, or about 19 grams of alcohol. A bottle of wine split between two people gives each person roughly 2.5 standard drinks, not two. Once you start running the numbers, the gap between perceived and actual intake becomes surprisingly wide.