People often ask me, “How long do wines last after being opened?”. Not sure why they ask me because I usually don’t have this problem.
The long answer…
After pouring wine you should immediately reseal it with a good quality stopper. Don’t have one? Stick the cork back in.
There are two basic ways to keep an open bottle of wine fresh and protect it against oxidation: either the air in the bottle is pumped out or the remaining wine is covered with a protective blanket of gas. The simplest air-pump system is a small plastic device that allows wine drinkers to remove air from the bottle by hand. Vacu Vin’s Wine Saver ($15), is probably the best known and easiest to find. The simplest—and cheapest—form of protective gas comes in a can ($10-$15) and is sprayed directly into the bottle.
Without using gases or preservers, you can also simply reduce the amount of space for oxygen by pouring the wine in to a smaller bottle. A dessert (half) wine bottle or a snap lid that can be found at any home store works just fine.
The answer to the original question: Wine generally lasts about 3-5 days in the refrigerator before it goes totally flat and loses all aroma and flavor.
In the wine world there are always exceptions: some “important” wines actually need time to open and improve. As with foods like chili and lasagne, I have had a number of wines that taste better the next day after being left open over night.
Just like with wine, let your nose determine if something is safe to consume. If it has any unpleasant odor, throw it out.
Sharing a great resource from US Govt that also offers a FoodKeeper app, that answers most of our questions on storage, in refrigerator or freezer.
Tip: I try to write the date with a Sharpie, on whatever I store, for later use.