Wondering exactly how many calories are in a cup of grapefruit, whether you slice it fresh, segment it without juice, or measure it by weight? This grapefruit calories per cup calculator turns your portion size into a clear nutrition breakdown in seconds. Just enter the amount, choose your serving unit (a standard cup with juice, a drained cup, or grams), and select the variety — pink/red or white — and the tool calculates calories, carbs, net carbs, fiber, sugar, protein, and fat.
The calculator uses USDA nutrition reference values for raw grapefruit, adjusted for the edible portion weight of a typical cup. That makes it handy for calorie tracking, meal planning, low-carb and diabetic diets, and anyone who wants to see how this tart citrus fruit fits into their daily macros. You can also use the quick-fill buttons to estimate common portion sizes instantly.
Grapefruit is naturally low in calories and rich in vitamin C, so it is a refreshing way to add volume to a meal without blowing your calorie budget.
🍊 Portion Details
How to Use This Tool
This tool is designed for fresh raw grapefruit, not canned fruit or sweetened juice. Start by entering the amount in the number field — decimals are welcome, so you can calculate 0.75 cups or 1.5 cups as easily as whole numbers. Next, pick the serving unit that matches how you actually eat grapefruit: a cup of sections with juice, a drained cup, or a direct gram weight. Then choose either pink/red or white grapefruit and hit Calculate.
If you are estimating from memory, the quick-fill buttons are handy: 1 cup, 2 cups, 1 drained cup, and 200 g. After calculating, you will see the calorie total plus a full macronutrient grid that includes total carbs, net carbs, fiber, sugar, protein, and fat. The expanded breakdown shows every step of the math, so you can verify the numbers or adapt them to your own log.
The Math Behind It
The calculator applies USDA nutrient reference values per 100 g of edible raw grapefruit flesh and scales them to your portion weight. The core formula is:
Macronutrients use the same logic: grams of nutrient = portion weight × (nutrient per 100 g ÷ 100).
For pink/red grapefruit, the per-100 g figures used in this tool are approximately 42 kcal, 10.66 g total carbohydrate, 1.4 g fiber, 6.98 g sugars, 0.77 g protein, and 0.14 g fat. White grapefruit is lighter: about 33 kcal, 8.36 g carbohydrate, 1.1 g fiber, 7.31 g sugars, 0.69 g protein, and 0.10 g fat per 100 g. Net carbs are simply total carbohydrate minus fiber. These are average values from raw fruit; actual numbers fluctuate slightly by growing region, ripeness, and cultivar. The source data is maintained in USDA FoodData Central (fdc.nal.usda.gov).
Worked Examples
Example 1: 1 cup of pink/red grapefruit sections with juice. A typical cup weighs about 230 g, so the math is 230 × 42 ÷ 100 = 96.6 kcal. The same portion contains about 24.5 g total carbs, 3.2 g fiber, 16.1 g sugar, and 1.8 g protein.
Example 2: 150 g of white grapefruit segments. At 33 kcal per 100 g, this gives 150 × 33 ÷ 100 = 49.5 kcal. Net carbs come to roughly 150 × (8.36 − 1.10) ÷ 100 = 10.9 g.
Example 3: 2 cups of pink/red sections. Two cups weigh about 460 g. Calories = 460 × 42 ÷ 100 = 193.2 kcal, and fiber = 460 × 1.4 ÷ 100 = 6.4 g.
Reference Data: Grapefruit Nutrition per 100 g
The table below summarizes the values used by the calculator. Treat them as helpful averages for meal planning rather than laboratory-exact measurements.
| Nutrient | Pink / Red (per 100 g) | White (per 100 g) |
|---|---|---|
| Calories | 42 kcal | 33 kcal |
| Total carbohydrate | 10.66 g | 8.36 g |
| Net carbs | 9.26 g | 7.26 g |
| Fiber | 1.4 g | 1.1 g |
| Sugars | 6.98 g | 7.31 g |
| Protein | 0.77 g | 0.69 g |
| Fat | 0.14 g | 0.10 g |
For additional context, the general nutrition profile of grapefruit is covered in the Wikipedia article Grapefruit.
Factors That Affect Accuracy
- Cup volume differs from weight. A cup of grapefruit packed tightly will weigh more than a loosely filled cup. The values assume a standard 230 g cup with juice and 180 g drained cup.
- Variety and ripeness matter. Pink/red grapefruit are usually sweeter and slightly more calorie-dense; very ripe fruit can contain a bit more sugar.
- Refuse is excluded. Peels, pith, and seeds are not edible portion. If you weigh a whole fruit, subtract the peel and pith before entering the number.
- Processed products are not covered. Canned grapefruit in syrup or juice, grapefruit juice, and sweetened segments have very different calorie counts. Check the nutrition label for those items.
Frequently Asked Questions
How many calories are in a whole grapefruit?
A medium pink/red grapefruit yields roughly 150–160 g of edible flesh, which works out to around 65–70 calories. A very large fruit can exceed 100 calories, while a white grapefruit of the same size will be a little lower.
Is grapefruit keto-friendly?
Yes, in moderate portions. A half-cup of pink/red sections provides roughly 10.6 g net carbs, which can fit into most low-carb diets if planned carefully. If you are on a strict keto plan, weigh the fruit and count the net carbs against your daily allowance.
Why does the drained cup have fewer calories?
A drained cup contains about 180 g of fruit vs. 230 g for a cup with juice. The difference is mostly the liquid you pour off, so the nutrition estimates shift accordingly.