What is the standard drink size of Full Strength Beer?

• A. 469 mL
• B. 32 mL
• C. 313 mL
• D. 268 mL

Answer: (D)

The amount that counts as one standard drink depends on how much pure alcohol is in the drink. A standard drink is defined as about 10 grams of alcohol. To find how much full‑strength beer gives you that amount, think about how much ethanol is in the beer and the beer’s alcohol by volume (ABV).

If beer is around 5% ABV, that means 5 mL of ethanol per 100 mL of beer. To get roughly 12.7 mL of ethanol (since 10 g of ethanol is about 12.7 mL, given ethanol’s density), you’d need roughly 12.7 / 0.05 ≈ 254 mL of beer. Accounting for rounding and slight variation in ABV, this ends up around 250–270 mL. The option near that range, about 268 mL, best represents one standard drink of full-strength beer.

So, one standard drink of full-strength beer is a bit over a quarter of a litre, not a full can or pint, and much less than a litre. The other amounts would give you more or less than the 10 g of alcohol used to define a standard drink.