Don't forget nonalcoholic drinks, such as this Sparkling Berry Punch.
On the average, expect guests to drink 2 drinks or servings of a nonalcoholic beverage the first hour and 1 each hour thereafter. Remember, people drink more when the weather is warm.
If you plan to serve bar drinks, you should allow 1 1/2 ounces of liquor for each drink. That means you'll get about 16 drinks from each 750-milliliter bottle (fifth) of liquor. Allow about a quart of mixer -- carbonated water, tonic water, or ginger ale -- for every 3 persons.
When serving wine, plan on one 750-milliliter bottle for every two guests (one bottle for every 3 to 4 guests if the wine will be served only during a meal). If you prefer to buy the large 1.5-liter bottle of wine, it will serve 4 guests (6 to 8 guests if served only during a meal).
When ordering beer for a party, allow about 12 ounces per guest for every half hour to hour. For a large crowd, you might want to buy a keg.
Always have some nonalcoholic beverages on hand. Besides having juices, bottled water, lemonade, soda and/or iced tea, consider nonalcoholic wines and beers.
If you're uncertain about how much to buy, ask your beverage store if you can return any unopened bottles. If you entertain frequently, you may want to plan ahead and shop in quantity.