One serving of alcohol in the United States contains 14 grams (0.6 fluid ounces) of pure alcohol. That’s the fixed amount, regardless of what you’re drinking. What changes is the size of the glass, because different drinks have different alcohol concentrations. A 12-ounce beer, a 5-ounce glass of wine, and a 1.5-ounce shot of liquor all contain roughly the same amount of pure alcohol.
Standard Serving Sizes by Drink Type
Since every type of alcohol has a different strength, the pour size adjusts to keep each serving at that 14-gram benchmark. Here’s what one standard drink looks like in practice:
- Regular beer (about 5% ABV): 12 fluid ounces, or one typical can or bottle
- Wine (about 12% ABV): 5 fluid ounces, which is less than you might expect from a restaurant pour
- Distilled spirits like vodka, whiskey, rum, or gin (40% ABV / 80 proof): 1.5 fluid ounces, or one standard shot
Those numbers assume typical alcohol concentrations. Many drinks don’t fit neatly into these categories. A craft IPA at 9% ABV has nearly twice the alcohol of a regular beer. A generous restaurant wine pour of 8 ounces is actually closer to 1.5 standard drinks. A strong cocktail made with two shots contains two servings before you even add any mixers.
How to Calculate Drinks in Any Container
If you’re drinking something that doesn’t match those standard categories, there’s 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 glass is nearly two and a half servings.
For spirits labeled by “proof” instead of ABV, divide the proof number in half to get the ABV. An 80-proof bourbon is 40% ABV. A 94-proof gin is 47% ABV.
This formula is especially useful for tallboy cans, bottles of wine (which contain about five standard drinks, not three or four), and mixed drinks where the bartender may pour more than 1.5 ounces of liquor.
Calories Per Serving
Alcohol carries roughly 7 calories per gram on its own, and most drinks add more through carbohydrates and sugars. Here’s what one standard serving typically delivers:
- Light beer (12 oz): about 103 calories
- Regular beer (12 oz): about 153 calories
- Craft or high-ABV beer (12 oz): 170 to 350 calories
- Red wine (5 oz): 121 to 129 calories, depending on the varietal
- White wine (5 oz): about 128 calories
- 80-proof spirits (1.5 oz): 97 calories, with no carbs or sugar (before mixers)
- 94-proof spirits (1.5 oz): 116 calories
- Dessert wine (3.5 oz): 157 to 165 calories in a smaller pour
Keep in mind that cocktails add calories from syrups, juices, and cream. A margarita or piña colada can easily reach 300 to 500 calories, even if it contains only one or two standard drinks worth of alcohol.
Recommended Limits
The Dietary Guidelines for Americans set moderate drinking at 2 drinks or fewer per day for men and 1 drink or fewer per day for women. That limit applies to any single day, not as an average across the week. In other words, you can’t “save up” a week’s worth and have seven drinks on Saturday.
These limits are built around the standard 14-gram serving. If your actual pour is larger than the standard size, or your beer has a higher ABV, you may be consuming more servings than you realize.
Why U.S. Servings Differ From Other Countries
If you’ve seen different numbers elsewhere, it’s because countries define a “standard drink” differently. In the UK, the basic unit of alcohol is 8 grams of pure alcohol, roughly 57% of a U.S. standard drink. The NHS describes this as about the amount of alcohol an average adult processes in an hour. Australia uses 10 grams, Canada uses about 13.5 grams, and Japan uses nearly 20 grams. So a “drink” in one country is not the same as a “drink” in another, which matters if you’re reading health guidelines from an international source.