There are approximately 10 to 30 grapes in 1 cup, depending on the variety being measured. There are over 1,000 grape varieties, in shades of red, yellow, green and purple, ranging in size from 1/2 inch to nearly 2 inches in diameter.
One pound of grapes equals approximately 2.5 cups. A 1-cup serving of table grapes contains 104 calories, 3 milligrams of sodium, 27 grams of carbohydrates, 23 grams of sugar and 1 gram of protein. Grapes can be stored, unwashed, in the refrigerator for 5 to 7 days. Washing grapes before refrigerating causes them to spoil at a faster rate. Grapes can also be frozen for up to 12 months when stored in an airtight, freezer-safe container.