We generally recommend the following rule of thumb: 1.5 glasses per person for the first hour and 1 glass per hour for every hour after. For example, if there will be 100 guests at a 3-hour cocktail party, you would order (1.5 x 100) + (1 x 100) + (1 x 100) = 350 glasses. Please consider the amount and types of beverages you will be serving in addition to your guests’ preferences when determining your exact quantities.