One standard drink in the United States contains about 14 grams (0.6 fluid ounces) of pure alcohol. That’s the benchmark used by health agencies, but the actual volume in your glass depends entirely on what you’re drinking, because different beverages have very different alcohol concentrations.
What One Drink Looks Like by Beverage
Since beer, wine, and spirits vary widely in alcohol content, the same 14 grams of pure alcohol translates to very different pour sizes:
- Regular beer (5% ABV): 12 fluid ounces, which is one standard can or bottle.
- Table wine (12% ABV): 5 fluid ounces, roughly half a typical wine glass filled.
- Distilled spirits (40% ABV / 80-proof): 1.5 fluid ounces, a single shot glass.
These are the reference points the National Institute on Alcohol Abuse and Alcoholism uses. The key idea is that a can of beer, a glass of wine, and a shot of vodka all deliver roughly the same amount of alcohol to your body, even though the liquid volumes are quite different.
Why Your Actual Drink Often Isn’t “One Drink”
The standard drink is a measurement tool, not a description of what you’ll actually be served. A craft IPA at 8% ABV in a 16-ounce pint glass contains more than twice the alcohol of one standard drink. A generous restaurant wine pour of 8 ounces at 14% ABV is over two standard drinks. A mixed cocktail with two ounces of liquor plus a liqueur is easily 1.5 to 2 standard drinks or more.
To figure out how many standard drinks are in any container, you can use a simple formula from the Washington State Liquor and Cannabis Board: multiply the volume in ounces by the ABV (as a decimal), then divide by 0.6. So a 16-ounce beer at 7% ABV works out to (16 × 0.07) / 0.6, which equals about 1.87 standard drinks. That single pint is nearly two drinks by the medical definition.
How One Drink Affects Your Body
For a person of average build, one standard drink raises blood alcohol concentration (BAC) by roughly 0.01% to 0.03% over the course of an hour. That’s a small increase, generally below the threshold where most people notice significant impairment. Your liver processes alcohol at a fairly steady rate of about one standard drink per hour, so spacing drinks at that pace keeps BAC from climbing.
Body weight, sex, food in your stomach, medications, and genetics all shift this number. A smaller person will see a higher BAC from the same drink than a larger person. Women typically reach higher BAC levels than men after the same amount of alcohol, partly because of differences in body water content and enzyme activity.
Current U.S. Drinking Guidelines
The CDC defines moderate drinking as two drinks or fewer per day for men and one drink or fewer per day for women. The Dietary Guidelines for Americans frames it slightly differently: adults of legal drinking age should either not drink or drink in moderation. These limits are based on the standard drink definition of 14 grams of pure alcohol, so if your actual drinks are larger or stronger than the standard, you’ll hit those limits faster than you might expect.
Standard Drinks Vary by Country
If you’ve read health advice from other countries and the numbers seemed off, that’s because not everyone defines “one drink” the same way. In the UK, the standard unit is 8 grams of pure alcohol, nearly half the size of the U.S. standard drink. Australian guidelines use 10 grams. Canadian standards also use about 13.5 grams. This means that drinking guidelines from different countries aren’t directly comparable without converting to the same unit first. A UK recommendation of 14 units per week, for example, is not the same as 14 U.S. standard drinks per week.
Practical Ways to Track Your Intake
Knowing the math is useful, but most people don’t carry a calculator to a bar. A few habits make it easier to keep track. At home, measure your wine with a measuring cup once or twice so you can eyeball 5 ounces going forward. Most people are surprised at how small it looks in a large wine glass. For beer, check the ABV on the label and mentally round up if it’s above 5%. A 7% beer in a pint glass is close to two drinks. For cocktails, ask the bartender how many ounces of liquor go in, or simply count each shot as one drink.
If you’re pouring spirits at home, a standard jigger holds 1.5 ounces, which is exactly one standard drink of 80-proof liquor. Free-pouring almost always ends up heavier than that.