The calories in white wine come from alcohol and sugar, with alcohol containing nearly twice the calories. Alcohol has 7 calories per gram, while sugar and simple carbohydrates contain only 4 calories per gram.
The sugar content in wine varies from slightly less than 1 gram per 5.4-ounce glass to 16 grams or more per glass for sweet wines. A dry white averages 112 calories per glass, while a sweet white has about 144 calories per glass. Champagne averages 2.5 grams of sugar, or 115 calories per glass.
White wines with the lowest alcohol content include dry rieslings and Vouvrays, usually at 12.5 percent or less alcohol by volume, followed by white Burgundies, Bordeauxs, sauvignon blancs and pinot grigios at between 12.5 and 13.5 percent. Whites with the highest alcohol content include chardonnays, Sauternes, chenin blancs and fortified wines such as sherries, with 14 percent or more alcohol by volume.