How many bottles of vodka for cocktail party?

A 26 oz. (750 ml) bottle of vodka yields 17 Servings of 1 ½ oz. (45 ml) each.

A 40 oz. (1.14 L) bottle of vodka yields 25 Servings.

The average cocktail party lasts three hours. Allow three drinks per person, more, depending on your guests' drinking habits. A buffet or sit-down dinner is usually about four hours long. Figure three to four drinks per person.