Will the alcohol evaporate from an open bottle of wine?

Ask Dr Vinny

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,

If I open a wine bottle, drink half, insert the cork back quickly, and let it sit for six months, will the alcohol level be reduced?

—Amir, California

Dear Amir,

No, but the wine will definitely taste different, and that might include the alcohol sticking out more. Alcohol is determined during the fermentation process, when the sugar in grapes is converted to alcohol. Once the fermentation process is complete, the alcohol level will remain constant. It’s chemistry!

But after six months of being open—even if you cork a bottle back up promptly—a wine will start to oxidize. As soon as you open a bottle you expose it to air, and as soon as you pour some wine out, you’ve increased the surface area and let more air in. I’m guessing after all of that time, the wine would taste nutty and flat, and the fruit flavors would fade, leaving you with just as much alcohol but not nearly as much flavor.

I should mention that it is true that alcohol would evaporate at a slightly faster rate than the wine’s water content, but that’s more of a pouring-the-wine-into-a-shallow-pan-and-pointing-a-fan-at-it (or put it on a stove to make a reduction sauce) scenario than what you’ve described.

—Dr. Vinny

Alcohol Level Ask Dr. Vinny

More In Dr. Vinny

What is “reverse osmosis” in relation to wine? How and why is it used?

Wine Spectator's expert Dr. Vinny explains the science (and the motivation) behind the …

Nov 28, 2022

I need advice on Thanksgiving wines. Which wines pair best with turkey and sides?

Wine Spectator's expert Dr. Vinny offers advice on selecting wines for the Thanksgiving …

Nov 21, 2022

What is a “second wine”?

Wine Spectator's expert Dr. Vinny explains the "second wine" concept and what it means in …

Nov 14, 2022

Is it bad if an old bottle of wine has sediment in it?

Wine Spectator's expert Dr. Vinny explains that sediment happens—and how to deal with it.

Nov 7, 2022

Is it OK to change my mind about a wine after I've approved a sommelier to serve it?

Wine Spectator's expert Dr. Vinny explains that there's a reason that sommeliers show …

Oct 31, 2022

How should I organize a tasting of 4 wines paired with 4 chocolates?

Wine Spectator's resident wine expert Dr. Vinny offers suggestions for organizing food and …

Oct 24, 2022