Boxed wine has gained in popularity in recent years. More often, people are turning to boxed wine to save money or reduce their environmental impact. And because boxed wine stays fresh longer than bottled wine, they can, in theory, drink only one or two glasses per day without ruining the wine. How many glasses you get out of a box of wine depends on the size of your pours.
According to About Boxed Wine, a website managed by Scholle Packaging, which produces "bag-in-box" packaging, there are 20 glasses of wine in a 3-liter box, and 33 glasses in a 5-liter box.
According to the "Ultimate Bar Book: The Comprehensive Guide to Over 1,000 Cocktails," by Mittie Hellmich, a wineglass used for red wine holds 10 to 14 oz., and a wineglass used for white wine holds 6 to 12 oz. A liter is equal to 33.8 oz, and 3 liters is equal to 101.4 oz. A 5-liter box holds 169 oz.
Assume you're pouring 10-oz. glasses. A 3-liter box would yield 10 glasses of red wine with a little splash left over. You'd get 17 glasses from a 5-liter box.
If you're pouring 6-oz. glasses, a 3-liter box of wine would provide 17 glasses of white wine, one of which will contain slightly less liquid than all the others. A 5-liter box would provide 28 glasses with a splash left over.
Using the same standards, a 750-milliliter (25.35-oz) bottle of red wine would yield two and a half glasses.