How much alcohol is in one cocktail?

A standard cocktail contains roughly the alcohol of 1.5 to 2 standard US drinks. A typical 2-oz spirit cocktail (Martini, Negroni, Manhattan) is about 1.5 standard drinks; a Long Island Iced Tea is closer to 3 to 4 standard drinks.

A US standard drink contains 0.6 oz (14 grams) of pure ethanol. Common cocktails calculated: (1) Martini (2.5 oz gin at 40% ABV plus 0.5 oz vermouth at 18% ABV) = 1 oz pure alcohol = 1.7 standard drinks. (2) Negroni (1 oz gin at 40% plus 1 oz Campari at 24% plus 1 oz sweet vermouth at 16%) = 0.8 oz pure alcohol = 1.3 standard drinks. (3) Margarita (2 oz tequila at 40% plus 1 oz Cointreau at 40% plus 1 oz lime) = 1.2 oz pure alcohol = 2 standard drinks. (4) Old Fashioned (2 oz bourbon at 40%) = 0.8 oz pure alcohol = 1.3 standard drinks. (5) Long Island Iced Tea (0.5 oz each of vodka, gin, rum, tequila, triple sec at 40% each) = 1 oz pure alcohol per drink — same as a Martini, but most people drink them faster. The dilution from ice does not reduce the alcohol — it stays the same total grams; only the volume is larger and the perception is softer. Pace and food intake matter much more than which cocktail you choose. CDC moderate-drinking guidance is up to 2 standard drinks per day for men, 1 for women.