In the United States, one standard drink contains 0.6 fluid ounces (14 grams) of pure alcohol. That’s the amount found in 12 ounces of regular beer, 5 ounces of wine, or 1.5 ounces of distilled spirits. The key detail most people miss: it’s not about the size of the glass or the type of beverage. It’s about how much pure alcohol is in it.
What Counts as One Standard Drink
The U.S. federal government defines one alcoholic drink equivalent as any beverage containing exactly 14 grams of pure alcohol. In practical terms, that translates to three common servings:
- Beer: 12 fluid ounces at 5% alcohol by volume (ABV)
- Wine: 5 fluid ounces at 12% ABV
- Distilled spirits: 1.5 fluid ounces at 40% ABV (80 proof)
Each of these contains the same amount of pure alcohol, even though the glass sizes look completely different. A pint of light beer and a small pour of whiskey can deliver identical amounts of alcohol to your body.
Why Your Actual Drink Probably Isn’t “One Drink”
The standard drink definition assumes very specific ABV percentages, and many popular beverages don’t match them. A craft IPA can easily run 7% to 9% ABV, meaning a single 12-ounce bottle contains closer to 1.5 or even 2 standard drinks. Many red wines sit at 14% or 15% ABV rather than the assumed 12%, so a 5-ounce glass of Zinfandel is more than one standard drink.
Pour sizes also tend to be larger than people realize. While 5 ounces is the standard wine pour, many restaurants fill the glass to its widest point, which lands between 5 and 6 ounces. When you order liquor neat or on the rocks, the typical bar pour is 2 ounces rather than the 1.5 ounces that equals one standard drink. A cocktail with two types of spirits can contain three or four standard drinks in a single glass, even though it feels like “one drink.”
How to Calculate Standard Drinks in Any Beverage
You can figure out the number of standard drinks in any alcoholic beverage 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 beer at 6% ABV: 16 × 0.06 = 0.96, divided by 0.6 = 1.6 standard drinks. That single pint is more than one and a half drinks by the official definition.
This math is especially useful for higher-ABV beers, generous wine pours, and cocktails where the total spirit content isn’t obvious. A 9-ounce pour of 14% wine, for instance, works out to about 2.1 standard drinks.
What One Drink Does to Your Body
A single standard drink raises blood alcohol concentration (BAC) by roughly 0.02% in an average adult. That’s well below the 0.08% legal driving limit in most states, but the effect varies widely based on body weight, sex, food intake, and how quickly you’re drinking. A 120-pound person will experience a noticeably higher BAC from the same drink than a 200-pound person.
Federal dietary guidelines use the standard drink as the building block for moderate drinking recommendations: up to 1 drink per day for women and up to 2 drinks per day for men, on days when alcohol is consumed. Binge drinking is defined as reaching a BAC of 0.08% or higher, which typically corresponds to 4 or more drinks for women or 5 or more drinks for men within about two hours.
Standard Drinks Vary by Country
The 14-gram U.S. definition is just one of many. The World Health Organization defines a standard drink as 10 grams of alcohol, but most countries set their own number. The range is dramatic: a standard drink in the United Kingdom and Iceland contains just 8 grams of alcohol, while Austria’s standard drink contains 20 grams. That means “one drink” in Austria holds two and a half times as much alcohol as “one drink” in the UK.
This matters if you’re reading international health guidelines or comparing drinking recommendations across countries. A guideline recommending “no more than two drinks per day” means very different things depending on which country’s standard drink is being used. When in doubt, focus on the grams of pure alcohol rather than the number of drinks.
Checking the Label
Most beer and wine labels list ABV, which gives you everything you need to do the math. For cocktails and mixed drinks, you’ll need to estimate the total amount of spirits used. A useful rule of thumb: any time you’re drinking something stronger than 5% beer, larger than the standard serving size, or mixed with multiple spirits, you’re likely consuming more than one standard drink per glass. Keeping the 14-gram benchmark in mind helps you track your actual intake rather than just counting glasses.