A standard drink in the United States contains 0.6 fluid ounces of pure alcohol. That’s about 14 grams. Every standard drink, whether it’s beer, wine, or a shot of vodka, contains this same amount of pure alcohol. The total liquid in your glass varies widely, but the actual alcohol inside stays consistent.
What Counts as One Standard Drink
Because different beverages have different alcohol concentrations, the serving size changes to keep the pure alcohol content at that 0.6-ounce mark. Here’s how that breaks down:
- Beer (5% ABV): 12 ounces, a typical can or bottle
- Malt liquor (7% ABV): 8 ounces, noticeably smaller than a full pint
- Wine (12% ABV): 5 ounces, roughly half a standard wine glass
- Distilled spirits (40% ABV / 80-proof): 1.5 ounces, a standard shot
Each of these contains the same 0.6 ounces of pure ethanol. The math is straightforward: multiply the volume of the drink by its alcohol percentage. A 12-ounce beer at 5% gives you 0.6 ounces of alcohol (12 × 0.05 = 0.6). A 1.5-ounce shot at 40% gives you the same (1.5 × 0.40 = 0.6).
How “Proof” Relates to Alcohol Percentage
Proof is simply double the alcohol-by-volume (ABV) percentage. An 80-proof whiskey is 40% alcohol. A 100-proof bourbon is 50% alcohol. If you’re holding a bottle that lists proof instead of ABV, divide by two to get the percentage you need for calculating pure alcohol content.
Why Your Actual Drink Probably Contains More
The standard drink is a measurement tool, not a reflection of what you’re actually being served. In practice, most pours exceed standard drink sizes. A typical restaurant wine pour is 6 ounces, not 5. A generous home pour of whiskey can easily hit 2 or 3 ounces. A pint glass of beer is 16 ounces, not 12.
Craft beer creates an even bigger gap. Many craft IPAs and stouts run 7% to 9% ABV or higher. A 16-ounce pint of a 9% double IPA contains 1.44 ounces of pure alcohol (16 × 0.09), which is nearly two and a half standard drinks in a single glass. Compare that to a 12-ounce light beer at 4% ABV, which contains just 0.48 ounces of alcohol, less than one full standard drink.
Cocktails are especially tricky to estimate. A margarita or a Long Island iced tea can contain two, three, or even four standard drinks depending on how they’re mixed. The only reliable way to know is to track how much liquor goes in.
How to Calculate Any Drink
You can figure out the pure alcohol in any beverage with one formula: multiply the total fluid ounces by the ABV expressed as a decimal. Then divide by 0.6 to see how many standard drinks it equals.
For example, a 16-ounce pint of beer at 6% ABV: 16 × 0.06 = 0.96 ounces of pure alcohol. Divided by 0.6, that’s 1.6 standard drinks. A 6-ounce pour of wine at 14% ABV: 6 × 0.14 = 0.84 ounces of alcohol, or 1.4 standard drinks. Many beer and malt liquor labels don’t list ABV, so you may need to check the brewery’s website.
Standard Drinks Vary by Country
The 0.6-ounce (14-gram) standard is specific to the United States. Other countries define a standard drink differently. In the United Kingdom, one alcohol unit contains about 8 grams of pure alcohol, roughly 56% of a U.S. standard drink. In Australia, one standard drink is 10 grams, about 71% of the U.S. measure. If you’re reading health guidelines from another country, the number of “drinks” they recommend won’t translate directly to U.S. servings.
What the Guidelines Say About Limits
The Dietary Guidelines for Americans, 2020-2025 recommend that men limit alcohol to 2 standard drinks or fewer per day and women to 1 drink or fewer per day. These limits assume you’re using the actual standard drink size, not eyeballing your pour. Since most real-world drinks contain more than one standard serving, counting glasses and counting standard drinks are often two very different things.