There's no denying that grapes are a healthy food for almost everybody — but what exactly constitutes a serving size of grapes? Most expert sources agree that about 1 cup of grapes equals one serving for adults.
The Serving Size for Grapes
The USDA, which offers nutritional information for almost every food under the sun, describes 1 cup — or just over 150 grams, they say — as a typical serving size of grapes.
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That's regardless of the type of grapes you're considering. Because individual grape size can vary quite a bit between varieties, focusing on a standardized measurement like this makes more sense than counting out individual grapes or trying to quantify what "a bunch of grapes" might mean in terms of servings.
Another online tool that's helpful for building healthy eating habits, USDA's ChooseMyPlate, echoes that recommendation — but fleshes it out by adding that you can measure the cup of grapes either whole or cut up. If you're a counter, they also offer approximate quantities — emphasis on approximate — of 32 seedless grapes for a 1-cup serving, or 16 seedless grapes for 1/2 cup if you want to split up your servings.
If you have special dietary considerations, your ideal serving size might be a little different — and a doctor or registered dietitian is usually the right person to help you decide what that might look like for you. For example, the American Dietetic Association recommends that people with diabetes limit a serving of carbohydrate-containing foods to about 15 grams of carbohydrates.
If you're eating grapes, that works out to about 17 small grapes, or 3 ounces — or roughly equivalent to the USDA's estimate for a 1/2-cup serving.
Read more: Can Eating Grapes Help Me Lose Weight?
Nutritional Information for Grapes
Why should you include grapes in your diet? They're naturally sweet and have a lower calorie count than prepared foods, with about 104 calories per 1-cup serving size of grapes, according to the USDA. That serving of grapes also contains 30 milligrams of phosphorus, 14 milligrams of calcium and an impressive 288 milligrams of potassium, plus a smattering of vitamin C, several B vitamins, lutein and beta carotene.
If you struggle to drink enough water during the day, eating water-rich fruits like grapes can help. The USDA notes that in a 151-gram serving of grapes, a whopping 122 grams is water content.
And, finally, eating grapes helps satisfy the USDA's recommended serving size of 2 cups of fruit per day for most adults. The sole exception is women ages 31 years and older — the USDA recommends they eat 1 1/2 cups of fruit per day.
However, don't eat only grapes — eating a variety of fruits, in a wide variety of colors, will help ensure a balanced nutrient intake. And all that fruit can do you a world of good: As the USDA notes, fruits are usually rich in essential nutrients that most people don't get enough of, including fiber, potassium, vitamin C and folic acid.
Read more: Top 10 Healthiest Fruits and Vegetables
Although grape juice and other fruit juices do contain many of the nutrients found in the whole fruit, they don't include the healthful effects of all that fiber — so consume whole fruit when you can.