Alcohol can cost a pretty penny, especially if you're stocking up for a party. Next shindig, keep the liquid refreshments flowing with a simple formula.
Video site Howcast says that, as a rule of thumb, you should allow two drinks per guest for the first hour of your party and one drink for each additional hour. It's also important to keep in mind the kind of party you're throwing because an evening cocktail party will likely require more spirits than a lunch get-together. The post says that if you allow four drinks per guest, you should be amply covered.
Howcast also says that a guideline for a large party (which they don't define beyond that label) is 50% beer, 25% wine, and 25% liquor, which you should then adjust depending on if your party guests drink more wine than beer and so on.
BYOB not withstanding, check out the above video for the entire set of alcohol buying tips.
How to Buy Alcohol for a Party [Howcast]