Drink More Wine: By the numbers

Decisions made in the vineyard determine what's in the bottle.

click to enlarge Think of this story the next time you buy grapes at the supermarket. - TOMÁS CASTELAZO VIA WIKIMEDIA COMMONS
Tomás Castelazo via Wikimedia Commons
Think of this story the next time you buy grapes at the supermarket.

How many grapes are in a glass of wine? It’s an intriguing question that’s difficult to pin down, as there are several moving parts to the equation.

At its core, wine is about farming. The many decisions made in the vineyard determine what’s in the bottle. Canopy management and pruning affect the ripeness of grapes and how many berries are produced in each cluster. Low yields concentrate flavors and produce higher quality. The riper the grapes, the higher the sugars, and sugar, after all, is what becomes alcohol during the fermentation process.

So when a farmer looks at an acre, how many bottles of wine can the land produce?

Good question. First of all, what is an acre, or, in European winespeak, a hectare? Simply dial in an image that’s familiar. An acre is about 91 yards on a football field — the length of a exciting punt return. And a hectare is just under 2.5 acres.

For our purposes, we’ll stick to acres. Winemakers think in tons per acre. High-end wines producing low yields and following natural biodynamic protocol might only produce a single ton of grapes. Farmers looking for quantity using every state-of-the-art tool available can harvest 8 tons or more destined to become simpler — and therefore, much less expensive — wines. There are multiple factors based on geographic terroir or grape varietal to determine average yields, with vine and row spacing, vintage conditions, and the variety or age of grapes playing a part in each acre’s harvest. Let’s use 3 tons per acre, which is a standard harvest worldwide for a quality wine.

In order to produce our 3 tons of grapes, we’re going to need to plant at least 566 vines. These numbers are flexible and change according to the variables listed above, or by wine varietal. I’ve picked one instance to illustrate how many grapes are needed to create that favorite glass of wine for your drinking pleasure.

Every vine will produce approximately 40 clusters of 70 or so grapes. Our expectation is 8,000 clusters per ton, or 24,000 for our sample acre. One ton of fruit will deliver about 170 gallons of juice, or slightly less than three barrels of wine, each of which contains about 60 gallons that eventually become 25 cases or 300 bottles.

For comparison, since we easily think in terms of gallons, a case of wine equals 2.4 gallons. A standard bottle of wine is 750 milliliters and holds five glasses — unless you have giant stemware and a heavy hand.

What does this mean if we keep dividing? You have to crush between 600 and 800 grapes to make a bottle of wine. If we go with 700 grapes and divide by 5, each glass of vino consists of around two clusters, or about 140 grapes. A bottle of wine equals roughly 2.6 pounds of fruit.

Think about that the next time you buy grapes at the supermarket.