BUZZ: Hey, Marnie, I'm in charge of beverages for our office Christmas party, but I'm not sure how much wine to get. Any advice?

Marnie: Figuring out how much wine to buy for parties is always a challenge, since consumption can vary widely, but here are some rules of thumb I use: First, calculate the number of guests and the length of the event. I usually plan on one drink per person for the first half hour, then one more per hour thereafter.

Buzz: Ha! My friend Howard will go through twice that.

Marnie: Yes, there will be some who have more drinks than others, but also some who have only one glass, or who pass on alcohol entirely. In the end, they should more or less balance out.

Buzz: OK, what's the next step?

Marnie: Once you know how many drinks per person, you can figure out your needs based on servings per bottle. Standard-size (750-milliliters) bottles contain 5 servings of wine, or roughly 12 servings of stronger spirits, like vodka or whiskey.

Buzz: What about the bigger bottles or wine boxes? I might save money going that route.

Marnie: Many value wines come in a larger "magnum" bottle that holds 1.5 liters of wine, or 10 glasses. Wine boxes are very handy for entertaining and come in two main sizes - 5 liters, or 33 glasses, for bargain wines; and 3 liters, or 20 glasses, for those of superior quality. Don't forget that you'll want both white and red on hand, though.

Buzz: Really? I thought white wine is more of a summer thing.

Marnie: Not at all. When offering party guests a choice between white or red, I can almost guarantee that you'll find the split is close to 50/50. White wines may not get as much attention, but people do love them, especially at social events, where refreshment can be more important than powerful flavor. For example, there is no red grape on Earth as popular as the white-wine grape chardonnay, which has reigned supreme for decades. You'd do well to have one on hand for your party.

Buzz: Thanks for the secret formula, Marnie. How about some advice for my secret Santa?

Marnie Old is a local sommelier and

wine author known for practical

advice with real-world relevance.

Her newest book, Wine: A Tasting

Course, is an illustrated crash

course for the wine curious. Check her out at MarnieOld.com or follow her on Twitter at @MarnieOld. Buzz's musings are interpreted by Daily News Assistant Managing

Editor Gar Joseph.