How many calories are in watermelon?
Watermelon has 46 calories per 1 cup diced (152 g) — that's 30 calories per 100 g, roughly 2% of a 2,000-calorie day. Most of those calories come from carbohydrate.
USDA FoodData Central · raw · FDC 167765
Calories by portion
| Portion | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| 1 cup diced (152 g) | 46 | 0.9 g | 11.6 g | 0.3 g |
| 100 g | 30 | 0.6 g | 7.6 g | 0.2 g |
| 1 oz (28 g) | 9 | 0.2 g | 2.2 g | 0.1 g |
Where the calories come from
Protein 7% Carbs 88% Fat 5%
Calories computed from USDA per-100 g data (FDC 167765, SR Legacy). raw. The macro split uses general Atwater factors (protein and carbs ≈ 4 cal/g, fat ≈ 9 cal/g) and is approximate.
A cup of diced watermelon carries only about 46 calories — that comes straight from USDA’s 30 calories per 100 g for a 152 g cup. That makes watermelon one of the lowest-calorie fruits you can eat: a whole cup is barely 2% of a 2,000-calorie day, less than half a banana and well under grapes or pineapple. The reason is simple — watermelon is roughly 92% water by weight, so even a generous bowl costs very little energy while still tasting sweet and feeling like a treat.
Where the calories in watermelon come from
Watermelon is, before anything else, water — and what little energy it has is carbohydrate. Of those ~46 calories, about 88% come from carbohydrate (mostly natural sugar), with roughly 7% from its ~0.9 g of protein per cup and ~5% from a trace of fat. A cup holds only about 12 g of carbs, of which around 9 g is sugar. That’s the whole story: there isn’t much of anything besides water in watermelon, which is exactly why the cup lands at just 46 calories and why it can’t help with protein or staying power.
One of the best fruits for volume eating
On calorie density, watermelon sits at the very bottom of the fruit shelf — about 9 calories an ounce, roughly a third of a banana’s per gram — because it’s nearly all water. That’s its superpower as a snack: you can eat a big, satisfying bowl and barely register it against your daily total, which is textbook volume eating for anyone watching calories. The practical angle is to lean into it — keep cubed watermelon on hand as a sweet, hydrating swap for higher-calorie desserts on a hot day. To make it a more complete snack, crumble a little feta over the cubes or follow it with a scoop of Greek yogurt so it carries some protein alongside the water and sugar.
For the flip side of the macro picture, see protein in watermelon — and remember watermelon’s calories are about as light and honest as whole fruit gets.
Frequently Asked Questions
How many calories are in a cup of watermelon?
Only about 46 calories in one cup of diced fruit (152 g), based on USDA's 30 calories per 100 g (FDC 167765). That's one of the lowest-calorie servings of any fruit — watermelon is roughly 92% water, so a big bowl costs very little energy.
How many calories are in watermelon per 100 g or per ounce?
30 calories per 100 g, which is about 9 calories per ounce (28 g). That's an exceptionally low calorie density — about a third of a banana's per gram — because watermelon is mostly water with just a little natural sugar and no fat or starch.
Where do the calories in watermelon come from?
Almost entirely carbohydrate. Using standard Atwater factors, roughly 88% of watermelon's calories come from carbs (mostly natural sugar), about 7% from its ~0.6 g of protein per 100 g, and around 5% from its trace of fat. There's so little of anything but water that the whole cup lands at just ~46 calories.
Is watermelon good for weight loss?
It's one of the best fruits for it. At ~46 calories a cup and about 92% water, watermelon fills you up and satisfies a sweet craving for almost no energy cost — a textbook volume-eating food. You can eat a generous bowl and barely move your daily total, which makes it a smart hot-weather snack when you want something sweet and light.
How many calories are in two cups of watermelon?
Only about 92 calories for two cups of diced watermelon (304 g) — still less than a single banana. That's the appeal: even a big serving stays light because you're mostly eating water. It's about as close to a 'free' sweet snack as whole fruit gets, though the natural sugar is still real.
When was this data last verified?
2026-06-04, against USDA FoodData Central FDC 167765 (Watermelon, raw; SR Legacy). We re-verify reference pages periodically and update when the underlying USDA entry changes.
Whole-food values are USDA reference data, not a Labelgrade (that score is for branded packaged products). See our methodology and the TDEE calculator to turn this into a daily target.