A standard drink in the United States contains about 14 grams (0.6 fluid ounces) of pure alcohol. That’s the amount found in 12 ounces of regular beer at 5% alcohol, 5 ounces of wine at 12% alcohol, or 1.5 ounces of distilled spirits at 40% alcohol (80 proof). These three servings look very different in a glass, but they all deliver the same amount of alcohol to your body.
Why the Standard Drink Exists
The standard drink is a measurement tool, not a serving size. Bars, restaurants, and your own kitchen don’t necessarily pour in standard drink increments. A generous glass of wine might be 8 ounces instead of 5. A pint of craft beer is 16 ounces, not 12. A cocktail with two types of liquor can easily contain two or more standard drinks in a single glass. The standard drink gives you a consistent unit so you can track how much alcohol you’re actually consuming, regardless of what the drink looks like.
Common Drinks and Their Equivalents
Here’s where it gets practical. Each of these contains one standard drink:
- Regular beer: 12 ounces at 5% ABV (a typical can or bottle)
- Wine: 5 ounces at 12% ABV (smaller than most restaurant pours)
- Distilled spirits: 1.5 ounces at 40% ABV / 80 proof (a single shot)
Notice these are all based on specific alcohol percentages. Change the percentage or the volume and the math shifts quickly.
How to Calculate Standard Drinks
You can figure out how many standard drinks are in any beverage using 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 craft beer at 9% ABV works out to 16 × 0.09 ÷ 0.6 = 2.4 standard drinks. That single pint contains nearly two and a half drinks. A cocktail with 2.5 total ounces of 80-proof spirits comes to 2.5 × 0.40 ÷ 0.6 = 1.67 standard drinks.
If a bottle lists “proof” instead of ABV, divide the proof number in half to get ABV. An 80-proof whiskey is 40% ABV. A 100-proof bourbon is 50% ABV.
Where Real Pours Diverge From Standards
The biggest mistake people make is assuming one drink equals one standard drink. In practice, the two rarely line up. A standard wine pour is 5 ounces, but most restaurants serve 6 to 9 ounces per glass. A margarita or Long Island iced tea can pack three or more standard drinks into a single cocktail. Even beer has shifted: craft IPAs commonly run 7% to 9% ABV, and many are served in 16-ounce pints rather than 12-ounce glasses.
That 16-ounce 7% IPA? It contains 1.87 standard drinks. Order two of those and you’ve had nearly four standard drinks, not two. Running the formula on whatever you’re drinking gives you a much more accurate picture than simply counting glasses.
How Your Body Processes One Standard Drink
Your liver breaks down alcohol at a remarkably steady rate: roughly one standard drink per hour. This rate doesn’t change based on your size, how much water you drink, or whether you eat first (though food slows absorption into your bloodstream, it doesn’t speed up metabolism). Coffee, cold showers, and exercise don’t help either. Time is the only thing that clears alcohol from your system.
This means if you have four standard drinks over the course of an evening, your body needs approximately four hours to fully process the alcohol. If a single cocktail actually contained two standard drinks, you’re looking at two hours of processing from that one glass.
Moderate Drinking and Binge Drinking Thresholds
Health guidelines use standard drinks to define risk levels. The CDC defines moderate alcohol use as two drinks or fewer per day for men, and one drink or fewer per day for women. These aren’t averages over a week. Having seven drinks on Saturday doesn’t count the same as one per day.
Binge drinking is defined as five or more drinks for men, or four or more drinks for women, during a single occasion. By the standard drink math, this threshold is easier to hit than most people realize. Two 16-ounce craft beers at 8% ABV already total 4.27 standard drinks, which meets the binge drinking definition for women and nearly meets it for men.
Why the Number Differs by Country
The U.S. standard of 14 grams of pure alcohol is not universal. The United Kingdom defines a unit as 8 grams. Australia uses 10 grams. Japan uses 19.75 grams. If you’re reading health recommendations from another country, their “one drink” is a different quantity than the American standard drink. Always check which standard is being used before comparing guidelines across countries.