Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions , from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics .

Dear Dr. Vinny,

How many bottles of wine can be made from a 1-hectare vineyard?

—Edwyn M., England

Dear Edwyn,

I’ve answered a version of this question before, but it was about wine produced per acre, not per hectare. This is a great excuse to explain the metric unit of hectares to everyone here in the States, and to do some math!

Folks in the United States are familiar with the acre as a measurement of land. An acre is believed to have been defined back in the Middle Ages as the amount of land that could be plowed in one day with a yoke of oxen. It is 0.0015625 square miles, 4,840 square yards, or 43,560 square feet. In other words, it's a little smaller than a football field.

Elsewhere—and in just about every other wine-producing region in the world—the metric system is used. A hectare is a metric area equal to 100 square meters. A hectare contains about 2.47 acres, or an acre is about 40 percent the size of a hectare, in case you want to do the conversion in your head.

Back to your question, and lucky for you, I have a dear friend who’s a math professor who checked my work. There really are a lot of variables that will affect what’s known as a vineyard's "yield." Not just the types of grapes, but how far apart the vines are spaced, how old the grapevines are, what kind of weather the vintage had and how much thinning may have been done in the vineyard.

In the U.S., yields are described as tons per acre. Most vineyards produce on average between 2 and 10 tons of grapes per acre. Generally speaking, a ton of grapes produced enough wine to fill a little more than two standard barrels. Of course it depends on what kind of grapes, the skin-to-seed-to-juice ratio, and things like weather (rain just before harvest will add to the liquid content of the grapes), as well as the method of making red wine vs. white wine. But let’s assume that 1 ton of grapes is a little more than two barrels, and each barrel contains about 60 gallons, which translates to 25 cases, or 300 bottles. So 1 ton of grapes yields about 60 cases, or 720 bottles. A low-yielding 1-acre vineyard that yields 2 tons of grapes makes about 120 cases, or 1,440 bottles, while an acre that yields 10 tons produces about 600 cases, or 7,200 bottles.

Switching over to metric, yields are measured in hectoliter (100 liters) per hectare. One ton per acre is about 17.5 hectoliters per hectare, and most vineyards produce between 35 and 175 hectoliters per hectare. But if we’re still agreeing with my estimate that 1 ton is a little more than two barrels, and 1 acre is .404686 hectares, and vineyards yield between two and 10 tons per acre, the range of yield per hectare is 296 to 1,482 cases, or 3,558 to 17,791 bottles.

—Dr. Vinny