Macronutrients. Each one-cup serving of grapes contains 62 calories, 0.6 grams of protein, 0.3 grams of fat and 15.8 grams of carbohydrate, including 0.8 grams of fiber.(See Reference 1) This is about three percent of the daily 25-gram value for fiber for people who eat a 2,000-calorie diet.hile red seedless grapes aren't a great source of minerals, they do provide 176 milligrams of potassium, or five percent of the DV, per one-cup serving, as well as smaller amounts of magnesium, zinc, iron, calcium and phosphorus.