A typical serving of grapefruit (1/2 fruit, 123 g) has about 52 calories. Per 100 g: 42 kcal, 0.8 g protein, 10.7 g carbs, 0.1 g fat. The same 100 g carries 1.6 g of fiber and 6.9 g of sugar. Most of the energy comes from carbohydrate.
| Serving | Weight | Calories |
|---|---|---|
| 1/2 fruit | 123 g | 52 kcal |
| 1 cup sections, with juice | 230 g | 97 kcal |
| 100 g | 100 g | 42 kcal |
Half a grapefruit is a 52-calorie starter that takes ten minutes to eat. On the energy-density scale, 42 kcal per 100 g puts grapefruit at the very low end.
A typical serving (1/2 fruit, 123 g) has about 52 calories, and 100 g has 42 kcal. Calories scale with weight, so double the portion means double the number.
There are 0.8 g of protein in 100 g of grapefruit, which works out to about 1 g per serving (1/2 fruit). Treat it as an energy source rather than a protein source.
There are 10.7 g of carbohydrate per 100 g of grapefruit, or about 13 g in 1/2 fruit (123 g).
Every value on this page comes from USDA FoodData Central, entry 174673 (SR Legacy). Serving figures are converted from the per-100-g data, so rounding can shift a total by a calorie or two.
Snap a photo of your plate in Joules and the calories and macros for grapefruit are logged for you.
Get JoulesA note on accuracy: calculators like this one provide estimates based on population-level formulas — your real needs vary with genetics, muscle mass, medical conditions, and more. Results are for information only and are not medical advice, a diagnosis, or a prescription. Talk to a doctor or registered dietitian before making significant changes to your diet or exercise, especially if you have a health condition, are pregnant, or are under 18.
Nutrition data: USDA FoodData Central, FDC ID 174673 (SR Legacy). Serving calories are computed from the per-100-g values.
