A standard drink in the United States contains 0.6 fluid ounces (14 grams) of pure alcohol. That’s the fixed amount used in federal health guidelines, nutrition labels, and drinking recommendations, regardless of what type of beverage you’re holding. The container size changes depending on the drink, but the alcohol inside stays the same.
How Much Liquid Is One Standard Drink?
Because different beverages have different alcohol concentrations, the volume of liquid that equals one standard drink varies quite a bit. For the three most common categories:
- Regular beer (5% ABV): 12 fluid ounces, or one typical 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.
These numbers only hold at those exact alcohol percentages. Change the percentage and the math shifts, sometimes dramatically.
Why Your Drink Probably Isn’t “One Drink”
The standard drink definition assumes specific, moderate alcohol percentages that don’t reflect a lot of what people actually buy and order. A craft IPA at 7% or 9% ABV packs significantly more alcohol into the same 12-ounce can than a 5% lager. That single can could contain 1.4 to 1.8 standard drinks. Order a 16-ounce pint of a 9% double IPA at a brewery, and you’re looking at roughly 2.4 standard drinks in one glass.
Wine presents a similar problem. Many popular reds and whites now range from 13.5% to 15% ABV rather than the 12% used in the standard drink calculation. A 5-ounce pour of 15% wine contains about 1.25 standard drinks. If the restaurant is generous with the pour (and many are), you could easily reach 1.5 standard drinks per glass without realizing it.
Mixed drinks are the hardest to gauge. A margarita, Long Island iced tea, or craft cocktail can contain two, three, or even four standard drinks depending on the recipe, yet it arrives as a single serving. The one-glass-equals-one-drink assumption falls apart entirely with cocktails.
How to Calculate It Yourself
If you want to know exactly how many standard drinks are in any beverage, there’s a simple formula from the Washington State Liquor and Cannabis Board:
Number of standard drinks = (volume in ounces) × (ABV as a decimal) ÷ 0.6
For example, a 16-ounce pint of 6% beer: 16 × 0.06 = 0.96, divided by 0.6 = 1.6 standard drinks. A 6-ounce glass of 14% wine: 6 × 0.14 = 0.84, divided by 0.6 = 1.4 standard drinks. The ABV is printed on virtually every bottle and can, so you always have the number you need.
How Your Body Processes One Standard Drink
Your liver breaks down alcohol at a remarkably steady pace: about one standard drink per hour. This rate doesn’t speed up if you drink coffee, eat food, take a cold shower, or exercise. Time is the only thing that clears alcohol from your system.
This means that if you have three standard drinks over the course of an hour, your body needs roughly three hours to fully metabolize that alcohol. Drinking faster than one standard drink per hour causes your blood alcohol concentration to climb, because alcohol enters your bloodstream much faster than your liver can process it. Understanding this rate is the practical reason the standard drink measurement exists in the first place: it gives you a unit you can count and pace.
What “Moderate Drinking” Means in Standard Drinks
Federal 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 use the standard drink as their unit of measurement, which is why getting the count right matters. If your nightly “one glass of wine” is actually a 7-ounce pour of 14.5% cabernet, you’re consuming closer to 1.7 standard drinks, not one.
The difference in guidelines between men and women reflects differences in body composition and alcohol metabolism, not an arbitrary distinction. Women generally have less body water to dilute alcohol and produce less of the enzyme that breaks it down in the stomach, leading to higher blood alcohol levels from the same amount.
Standard Drinks Vary by Country
There is no universal international definition of a standard drink. The U.S. sets it at 14 grams of pure alcohol, but other countries draw the line differently. Canada defines a standard drink as containing 17.05 milliliters of pure ethanol, which works out to about 13.45 grams. Australia uses 10 grams. The UK uses “units” of 8 grams each. Japan sets its standard at 19.75 grams.
This means drinking guidelines from different countries aren’t directly comparable. “Two drinks a day” in the U.S. is a different amount of alcohol than “two standard drinks” in Australia. If you’re reading health advice from an international source, check which country’s definition is being used before applying the numbers to your own habits.