How Many Calories Are in Grapefruit? | A Low-Cal Surprise

You probably know grapefruit as the tart, pink fruit that shows up on breakfast plates and in juice cartons. What’s less obvious is how few calories it actually carries. Compared to a banana or an apple, a serving of grapefruit looks almost like a freebie on your daily tally.

The exact number depends on size and how much you eat. Half a medium grapefruit (roughly 3¾ inches across) lands at 41 calories. A whole fruit of the same size gives you around 104. Those figures come from USDA data cited by the American Heart Association.

Grapefruit Calories by Size and Variety

Calorie counts shift slightly based on the fruit’s diameter and whether it’s pink, red, or white. A 100-gram serving of red or pink grapefruit provides 42 calories. That serving is about half a cup of segments or roughly two-thirds of a small fruit.

A large grapefruit – 4.5 inches in diameter – comes in at about 106 calories. Ruby Red and other common varieties fall in the same range because their sugar content is similar. White grapefruit is slightly less sweet but still within a few calories of the pink types.

The takeaway: no matter which shade you pick, you’re looking at a fruit that delivers very few calories per bite. Even a generous half-grapefruit serving is under 50 calories, which is less than most single pieces of toast or a small handful of almonds.

Why Grapefruit Earns a Spot in Weight-Loss Meal Plans

Grapefruit’s low calorie density is one reason it shows up on so many diet lists. But the fruit also brings other qualities that make it a standout for people watching their weight:

• High water content: Grapefruit is roughly 90% water. That means you get a satisfying volume of food for very few calories, which can help fill your stomach and curb cravings.
• Decent fiber: Half a medium grapefruit provides 2 grams of fiber – about 8% of the daily target. Fiber slows digestion and supports a feeling of fullness between meals.
• Low natural sugar: Despite its tangy-sweet taste, a whole medium grapefruit has only about 16 grams of sugar. For comparison, a medium apple has about 19 grams, and a banana has roughly 14 – but in a smaller volume.
• Vitamin C boom: Half a medium grapefruit delivers nearly half your daily vitamin C needs. That’s a big immune boost for a very small calorie investment.
• Associated with better diet quality: One peer-reviewed study found that people who eat grapefruit tend to have higher intakes of vitamin C, magnesium, potassium, and fiber, and their overall diet quality scores are higher.

None of this means grapefruit is a magic weight-loss food – diet quality always depends on the bigger picture. But swapping a higher-calorie snack for half a grapefruit is an easy way to cut 50 to 100 calories a day without feeling deprived.

How Its Calorie Count Compares to Other Fruits

Among common fruits, grapefruit sits near the bottom of the calorie chart. The USDA’s nutrition guide shows that grapefruit calories per 100g come to 42. Here’s how that stacks up against other fruits for the same 100-gram portion:

Fruit (100g raw)	Calories	Carbohydrates (g)
Grapefruit (red/pink)	42	10.7
Orange (navel)	49	11.8
Apple (with skin)	52	13.8
Banana	89	22.8
Strawberries	32	7.7
Blueberries	57	14.5

Grapefruit is noticeably lower in calories than apples and bananas. Only strawberries edge it out among the fruits listed. If you’re counting calories or carbs, a 100-gram serving of grapefruit is nearly half the energy of a banana and about 20% fewer than an apple.

What You Get Beyond the Calories

The fruit’s modest calorie count comes with a surprising nutritional payload. Here are the key nutrients in half a medium grapefruit and what they do:

1. Vitamin C – about 38 mg (50% DV). This antioxidant supports immune cells, helps collagen production, and may reduce oxidative stress. one medium grapefruit provides 100% of the DV, so even half gives you a strong dose.
2. Fiber – 2 grams (8% DV). Fiber aids digestion, steadies blood sugar, and contributes to satiety. That’s more fiber per calorie than many other fruits.
3. Potassium – roughly 150 mg. Potassium helps balance blood pressure and counteracts sodium. A whole grapefruit provides about 320 mg, similar to half a banana.
4. Magnesium – about 9 mg. This mineral supports muscle and nerve function and is often low in modern diets.

None of these numbers are massive on their own, but they add up fast when you eat grapefruit regularly. And because the fruit is so low in calories, the nutrient density – nutrients per calorie – is excellent.

Using Grapefruit in a Balanced Diet

Grapefruit fits easily into a variety of meal patterns. Per the whole grapefruit vitamin C overview from Johns Hopkins Medicine, one medium fruit covers your daily vitamin C requirement. That makes it a practical choice for a post-workout snack, a side with breakfast, or a base for a fresh salsa.

One important catch: grapefruit can interfere with certain medications. The fruit contains compounds that affect how your liver processes drugs like statins (for cholesterol), calcium-channel blockers (for blood pressure), and some allergy and anxiety medications. If you take any prescription drugs, check the label or ask your pharmacist before adding grapefruit to your daily routine.

For a quick nutrition snapshot, here’s what half a medium grapefruit gives you:

Nutrient	Amount in ½ medium grapefruit
Calories	41
Total fat	0 g
Carbohydrates	10.4 g
Fiber	2 g
Protein	0.8 g
Vitamin C	38 mg (50% DV)

To burn off the calories from a large grapefruit (about 106), a 155-pound person would need to walk briskly for roughly 30 minutes. That’s a small effort for a fruit that also delivers a heavy dose of vitamin C and hydration.

The Bottom Line

With 41 to 106 calories per serving – depending on size – grapefruit is one of the lowest-calorie fruits available. It pairs a high water and fiber content with a meaningful dose of vitamin C, making it a smart choice for weight management and general nutrition. Just remember to check for possible interactions with any medications you take.

Your best approach is to match your serving size to your daily calorie target and enjoy it fresh rather than juiced, since juice removes the fiber while keeping the sugar and calories similar.