It's one of the central questions of party planning, how much will people drink? How much should you buy? The most common estimate given for adults is 1 drink per hour, per person. So, if you're having 20 guests for a three hour cocktail party you'll need a total of 60 drinks.  Of course, you know your friends and their drinking habits best, and there are other things to consider.

The average bottle of wine should be five servings. So, for a three hour party with 20 wine drinking guests you would want 12 bottles of wine. But, if people are using non wine glasses or large wine glasses they will most likely over pour, so you may want extras on hand. As a general rule, more people drink white than red, and a few people will bring you bottles of wine as a gift.

If your party is casual and you expect a number of people to be drinking from cans or bottles you'll need more beverages on hand as people are likely to put down their drink and then forgot where it went. For some strange reason, this happens more with soda or water than beer. Very few people lose track of their beer.

If you're serving out of glasses or disposable cups, you'll also want to have extra available for the same reason.

If children will also be at the party, you'll want to plan 2-3 drinks per child (non alcoholic, obviously). Children are even more likely than adults to misplace water bottles or juice boxes, so buy the smaller sizes.

Of course, you can hire a bartending professional, who can ensure your party bar stays stocked!

What other basic party planning questions do you have? Let us know in the comments below.