Grapefruit

Q: How many calories in 0.5 medium (approx 4" dia) of grapefruit?

About 41 calories, with roughly 0.8g of protein. 0.5 medium (approx 4" dia) weighs about 128g. Use the slider above for any other portion.

Grab-and-go fuel that has not been engineered into a snack.

cal per 100 g

Portion explorer

How much are you eating?

Drag the slider or type grams. Everything below updates live.

= 4.5 oz

Calories

Protein

0.8g

Carbs

10.3g

Fat

0.1g

Protein 7% Carbs 90% Fat 3%

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Grapefruit is 7g of sugar, wrapped in 1.1g of fiber per 100g. That's what makes it not soda.

The fiber slows absorption; the sugar is not "free sugar" the way added sugar is. Whole fruit and juice are different foods nutritionally, even at the same sugar number.

Reverse calculator

Work backwards from your target.

To hit grams of protein, eat:

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For calories, eat:

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Burn it off

What per 100 g costs.

Minutes for a 155 lb (70 kg) adult to burn 32 cal. Adjust down for lighter, up for heavier.

Walking

min · 3.5 mph

Cycling

min · easy pace

Jogging

min · 5 mph

Swimming

min · freestyle

Estimates from the Compendium of Physical Activities. Real burn depends on weight, intensity, and fitness.

The chef's caveat

Ripeness matters

A greener grapefruit has more starch and less sugar; a spotty one is the reverse. Total calories barely move, but if you are tracking blood sugar or fiber-vs-sugar ratio, ripeness is a real variable — not a rounding error.

Full nutrient panel · per 100 g

What else is in there.

From USDA FoodData Central (SR Legacy). %DV against the FDA 2,000-calorie reference.

Fiber1.1 g4%

Sugar6.98 g—

Saturated fat0.014 g0%

Cholesterol0 mg0%

Sodium0 mg0%

Potassium139 mg3%

Calcium12 mg1%

Iron0.09 mg1%

Magnesium8 mg2%

Zinc0.07 mg1%

Vitamin C34.4 mg38%

Vitamin E0.13 mg1%

Vitamin A46 mcg5%

Vitamin D0 mcg0%

Vitamin B60.042 mg2%

Vitamin B120 mcg0%

Folate10 mcg3%

Niacin0.25 mg2%

Caffeine0 mg—

How it stacks

Compared to its neighbors.

per 100 g, as-served. Same portion, honest comparison.

Strawberry

Almost identical calories.

Cal32 Protein0.7 g Fat0.3 g

Watermelon

Almost identical calories.

Cal30 Protein0.6 g Fat0.1 g

Lemon Juice

10 fewer calories per 100g.

Cal22 Protein0.3 g Fat0.2 g

Common questions

The stuff people actually ask.

How many calories in 0.5 medium (approx 4" dia) of grapefruit?

About 41 calories, with roughly 0.8g of protein. 0.5 medium (approx 4" dia) weighs about 128g. Use the slider above for any other portion.

Does a ripe grapefruit have more calories?

Barely. As fruit ripens, starch converts to sugar — same calories, different molecule. What changes: sweeter taste, faster blood-sugar rise, softer texture. Total calories move maybe 3–5%.

Is grapefruit actually healthy, or is that marketing?

By the numbers on this page: fiber, vitamin C, potassium; sugar comes with its brake pedal (fiber).

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