Few things can end a party more quickly than running out of booze. But alcohol can be pricey, so to avoid ending up with gallons of vodka, use these rules of thumb: Each guest will drink an average of two drinks the first hour and one drink each hour thereafter, and 40 percent will drink beer, 30 percent will drink hard liquor, and 30 percent will drink wine. When calculating quantities, know that a 1-liter bottle of alcohol yields approximately 22 mixed drinks. Evite's Drink Calculator
lets you plug in the length of your party; how many light, average and heavy drinkers are attending; and what kind of alcohol you're serving. It then tells you how much to buy.