Lot's of people tell me one serving of wine is 5 ounces but I can't see how cause that sounds like 2 sips to me not one glass. Besides I already looked it up and it did say five ounces counts as one glass of wine but usually a proper sized glass of wine is actually 8-10 ounces so if I drink a 750 ml bottle... show more Lot's of people tell me one serving of wine is 5 ounces but I can't see how cause that sounds like 2 sips to me not one glass.