A standard drink contains 10 grams of pure alcohol. Which of the following approximates a standard drink?

• A. 30 ml 40% spirits
• B. 285 ml full-strength beer
• C. 100 ml wine
• D. 50 ml light beer

Answer: (A)

A standard drink is about 10 grams of pure alcohol, so you check a drink by turning its volume and its alcohol percentage into how many grams of ethanol it contains.

For the option with 30 ml at 40% ABV: the ethanol content is 30 × 0.40 = 12 ml of ethanol. Multiplying by the ethanol density (about 0.789 g per ml) gives roughly 9.5 g. That’s very close to 10 g, making it a good match for a standard drink.

The other options vary in how much ethanol they deliver. A large beer at around 5% ABV would give a bit more than 10 g (about 11 g), while 100 ml of wine (depending on the exact ABV, commonly near 12%) is also around 9–10 g. A small amount of low-ABV light beer is far short of 10 g. Overall, the 30 ml of 40% spirits is the clearest match to 10 g of alcohol.