In the United States, one standard drink contains 0.6 fluid ounces (14 grams) of pure alcohol. That’s the fixed amount, regardless of what you’re drinking. The glass size changes depending on the beverage, because beer, wine, and spirits all have different alcohol concentrations.
Standard Drink Sizes by Beverage
Since every standard drink delivers the same 14 grams of pure alcohol, stronger drinks come in smaller servings. Here’s how that breaks down in practice:
- Regular beer (5% ABV): 12 fluid ounces, which is one typical can or bottle.
- Table wine (12% ABV): 5 fluid ounces, roughly half a standard wine glass.
- Distilled spirits (40% ABV / 80 proof): 1.5 fluid ounces, a single shot.
These are the three reference points used by the CDC and the National Institute on Alcohol Abuse and Alcoholism. If a beverage’s alcohol percentage falls outside these ranges, the serving size shifts accordingly. A fortified wine like port or sherry, typically around 17% to 20% ABV, lands somewhere between table wine and spirits. A standard drink of port is closer to 3 to 3.5 fluid ounces rather than the 5 ounces you’d pour for a regular wine.
Where Real-Life Drinks Get Tricky
The standard drink measurements assume fairly typical alcohol percentages. In reality, what you’re actually served often doesn’t match those neat numbers.
Craft beers are a common source of confusion. Many IPAs and stouts run 7% to 9% ABV or higher. A 12-ounce pour of a 9% beer contains nearly twice the alcohol of a standard drink. You can estimate roughly: divide 0.6 (the ounces of pure alcohol in one standard drink) by the beer’s ABV as a decimal, then divide by the number of ounces in your glass. Or just remember that if a beer is noticeably stronger than 5%, a full pint is more than one standard drink.
Restaurant wine pours are another gap. A standard drink of wine is 5 ounces, and many restaurants do pour close to that. But plenty of places serve 5.5 or 6 ounces per glass, and some go as high as 8 ounces. A generous 6-ounce pour of wine at 12% ABV is about 1.2 standard drinks. That difference adds up over dinner.
Cocktails are the hardest to gauge. A margarita or a Long Island iced tea can contain two, three, or even four standard drinks depending on how it’s mixed. A simple drink like a gin and tonic with a single 1.5-ounce pour of spirits is one standard drink. Anything with multiple liquors or generous pours is almost certainly more.
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 if you drink coffee, eat food, or take a cold shower. Time is the only thing that clears alcohol from your system.
That one-drink-per-hour rate is an average. Body size, liver health, genetics, and biological sex all influence the actual speed. But the general rule is useful for pacing. If you’re having three standard drinks over three hours, your body is approximately keeping up with your intake. Three drinks in one hour means two of them are still waiting in line to be processed, and your blood alcohol level is climbing.
Moderate Drinking Guidelines
The current Dietary Guidelines for Americans (2020-2025) define moderate drinking as no more than 2 standard drinks per day for men and 1 standard drink per day for women. These are daily ceilings, not targets, and they aren’t meant to be “saved up” for a weekend. The guidelines also note that not drinking at all is a perfectly valid choice.
The difference between the male and female limits reflects differences in body composition and the way alcohol is metabolized. Women generally have less body water to dilute alcohol and lower levels of the enzyme that begins breaking it down in the stomach, so the same number of drinks produces a higher blood alcohol concentration.
Standard Drinks in Other Countries
If you’ve seen alcohol guidance from the UK or Australia, the numbers might look different. That’s because “one drink” isn’t defined the same way everywhere. In the UK, the basic unit of alcohol is 8 grams of pure alcohol, compared to 14 grams in the US. So a UK unit is a little more than half a US standard drink. Australia uses 10 grams as its standard. When reading international health recommendations, the drink limits aren’t directly comparable unless you convert to grams first.
This is worth keeping in mind if you’re following guidelines from a source outside your country. A recommendation of “no more than 14 units per week” in the UK (112 grams total) translates to about 8 US standard drinks per week.
A Quick Way to Estimate Any Drink
For any alcoholic beverage, you can estimate the number of standard drinks 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 7% IPA: 16 × 0.07 = 1.12, divided by 0.6 = roughly 1.9 standard drinks. A 6-ounce glass of 14% red wine: 6 × 0.14 = 0.84, divided by 0.6 = 1.4 standard drinks. This math takes seconds and gives you a much more accurate picture than guessing based on the number of glasses you’ve had.