A standard drink is a fixed amount of pure alcohol, not a fixed glass size. Because drinks vary in strength, the serving that counts as one varies too.
| Drink | Serving | ABV | Standard drinks |
|---|---|---|---|
| Regular beer | 12 oz | 5% | 1 |
| Light beer | 12 oz | 4.2% | 0.8 |
| Malt liquor | 8 to 9 oz | 7% | 1 |
| Table wine | 5 oz | 12% | 1 |
| Fortified wine | 3 to 4 oz | 17% | 1 |
| Spirits (shot) | 1.5 oz | 40% | 1 |
| Cocktail | Varies | Varies | 1 to 3 |
One standard drink is 14 g of alcohol. In the US, one standard drink contains about 14 g of pure alcohol. A strong cocktail or craft beer can count as two or more, so it is easy to underestimate.
See the Calories Per Drink Calculator and the Cocktail Mixing Ratios.