It's always hard to predict how a crowd will behave, and a lot depends on whether your friends like to drink, how many of them prefer wine or beer, how long the party will last, etc.

But by working with a few basic principles, you can usually come up with a good estimate. First, consider the standard wine bottle. It was originally one-fifth of a gallon in English-speaking countries -- a measure that, legend has it, represented a ration for one full-grown adult with dinner in olden times, when men were men, or wine was weaker.

Now turned metric at 750 ml, a reasonably close approximation of the traditional "fifth," it contains enough wine for five 5-ounce glasses, a fairly standard serving. If you assume that half of your guests will want wine, and that they'll average two glasses each (some drinking only one, others three or four), then you have a starting point for calculating your shopping list.

So, if you're inviting 90 pals to your lawn party, you might assume that half of them will take wine; assume an average of two glasses for each and you get 90 glasses, which divided by five makes 18 bottles or 1 1/2 cases of 12. I'd err on the high side by purchasing two cases (choosing a store that offers a discount for case purchases). Beer for the rest -- assume three bottles each -- and soft drinks for the teetotalers in attendance. The chances are that you'll have leftovers to stock your bar; but if you're thrifty, you might ask in advance if the wine shop is willing to take back unopened bottles.

I get this question so often, I'd love to hear if any of you have worked out effective formulas for calculating a party purchase. Write me at wine@wine-lovers-page.com. And, as always, please don't hesitate to drop us a line if you'd like to comment on our topics and tasting notes, suggest a topic for a future bulletin, or just talk about wine.

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FOOD MATCH: Red wine with seafood? This fruity-tart treat went surprisingly well with a spicy Cajun shrimp barbecue.

Begali 1997 Valpolicella Classico ($9.99)
Clear ruby. Fresh red-fruit aromas with floral hints of violets and aromatic new oak. Ripe and very tart, flavors follow the nose; there's a clean, pleasant bitter-almond quality in a long finish. U.S. importer: Pellegrini Family Vineyards, South San Francisco, Calif. (April 14, 1999)

FOOD MATCH: Fine with pan-grilled strip steaks.

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