The mathematics of wine: It all adds up |

The mathematics of wine: It all adds up

Kelly J. Hayes


What: Brunello di Montalcino Wine Dinner

Where: The Dallenbach Ranch, 2561 Frying Pan Road, Basalt

When: Wednesday, Aug. 19, 6 p.m.

How much: $175 plus tax and gratuity

Contact: Robin@; 970-279-5199

More info: Reservations will be limited due to County restrictions.

When I open a bottle of wine, one of the first things I pay attention to is the “ABV” number, or the alcohol by volume, on the label. It’s a requirement by law that it appear on every bottle and the percentage of alcohol gives me a general idea of how “big” the wine will be.

For example, I recently opened a bottle of one of my favorites, a 2017 “Relentless” from Shafer Vineyards in the Napa Valley. This is a syrah-based wine with 15.8% ABV. Now that is a substantial wine. But before I even tasted it, I had a figure in my mind and an idea of just what to expect.

ABV is just one number that is important in wine. But in fact the entire wine world is undergirded by numbers. The first numbers that matter are those constituting the size of a vineyard and what it can yield. In other words, how many grapes will a winemaker have to work with?

It is harvest season, so let’s look at some math on what goes on in a vineyard.

In this country, the standard mode of measurement for land is the acre. An acre is just shy of 44,000 square feet or a little smaller than a football field without the end zones. In other parts of the world the measurement used is the hectare, which is equal to just under 2.5 acres. We’ll use the acre because, well, we’re here in America.

An acre of land, based upon the variety of the grapes grown, the way they are trellised, and the desire for the level of quality, may host anywhere from 600 vines on the low end, with 11-by-6-foot spacing of the vines, to as many as 2,700 vines in a mass production vineyard. Each vine will produce, on average, approximately 40 clusters of grapes depending upon the techniques used by the grower. And each cluster will have somewhere between 75 and 100 grapes and will weigh over a pound.

A high-end winery will usually shoot for picking somewhere between two and four tons of grapes per acre. Using that as a model, that means in order to yield four tons of grapes you need about 800 vines.

So how much wine does four tons of grapes produce? Well, again on average, a ton of grapes will crush down to around 160 gallons of wine. Multiply four times (tonnage) by 160 (gallons) and you get 640 gallons of wine from your 800-vine acre.

Now, a traditional-sized wine barrel holds 60 gallons, which translates to around 25 cases. And there are 12 bottles of wine in each case. And 640 gallons would fill a little over 10 barrels. So if you multiply 10 barrels, by 25 cases, by 12 bottles, you get 3,000 bottles of wine on your planted acre, or just over 60 cases per ton.

All of these numbers vary based on the vintage and a plethora of other factors. But it is up to the winemaker to constantly monitor not just what is happening in the vineyard, but in the winery as well. Too much juice coming out of the vineyard can mean a shortage of fermentation space. It can also require more barrels. These calculations are imperative for each pick.

Then there is the math that goes into pricing a bottle or glass of wine in a retail location. Let’s take a look at some of the numbers of wine, starting with a bottle and working backward. A full bottle contains 750 milliliters of wine. That works out to 1/5 of a gallon or just over 25 ounces. Who cares? Well, start with a restaurant or bar that is selling premium wines by the glass.

The average pour, or the amount of wine served in a glass in a bar, is right around 5 ounces. If the bottle costs the bar, say $20 wholesale, and they are charging you $10, a reasonable price for a premium pour (likely more at that bottle price), then they are making $50 for the five glasses they pour from that bottle. Or two-and-a-half times more than they paid for it. You can see why wine sales can be the most profitable element in a restaurant.

In summation, knowing the numbers adds up to an even greater wine experience.