1 Cup Watermelon Calories, Carbs and Sugar

Watermelon is the classic summer fruit, and it earns a place in almost any weight loss plan. One cup of diced watermelon holds about 46 calories, so watermelon calories stay low even when you fill a big bowl. That makes it one of the easiest sweet snacks to enjoy without wrecking your daily numbers.

The numbers below cover watermelon nutrition facts by the cup, the carbs and sugar you actually eat, and whether the fruit really helps with weight loss. Every figure here comes from USDA style data and published research, so you can log your slice with confidence.

Watermelon Calories and Macros Per Cup

A standard cup of diced watermelon weighs about 152 grams and delivers roughly 46 calories. Per 100 grams the fruit is even lighter at about 30 calories, since watermelon is close to 91 percent water. Protein and fat sit under 1 gram each, so nearly all the energy comes from a small amount of natural sugar. In practice, 1 cup watermelon calories add up to only about 46, so the calories in a cup of watermelon rarely threaten a deficit.

How Many Calories in Watermelon by Serving

Serving size is where most people slip. A thin wedge cut from a whole melon can weigh close to 286 grams, which pushes it to about 86 calories. Snack straight from a family sized bowl and two cups reach near 92 calories before you notice.

One cup of diced watermelon is about 46 calories and roughly 91 percent water, one of the lowest calorie density snacks in the produce aisle.

Watermelon Nutrition Facts in a Full Chart

Here is the watermelon nutrition chart by common serving size. Calories and carbs scale directly with weight, so you can estimate any portion from these rows. Keep the cup as your anchor and the math stays simple.

Beyond the big three, a cup carries about 170 milligrams of potassium plus vitamin C and vitamin A. Watermelon is also the richest common source of lycopene, near 4,530 micrograms per 100 grams, more than a fresh tomato. For a protein rich food to pair with it, see our Greek yogurt protein guide.

Carbohydrates in Watermelon and Its Sugar

The carbohydrates in watermelon are almost entirely sugar. One cup holds about 12 grams of carbs, of which roughly 9 grams is natural sugar and only about 0.6 grams is fiber. That is why the fruit tastes sweet yet still fits a calorie deficit when you mind the portion.

Watermelon carbs are modest next to grains or bread. A cup of cooked rice runs far higher, as our rice calories per cup breakdown shows. Watermelon sugar content is real, though, so drinking it as juice or eating candied versions changes the picture fast.

A cup of watermelon carries about 12 grams of carbs and 9 grams of natural sugar, with a glycemic load low enough to keep a single serving in check.

Watermelon Glycemic Index and Blood Sugar

The watermelon glycemic index sits high, usually cited between 72 and 80. That sounds alarming until you factor in portion size. Because one serving has so few grams of carbohydrate, the glycemic load per cup lands near 4 to 5, which counts as low.

In plain terms, a single cup is unlikely to spike blood sugar the way the raw index suggests. Pairing the fruit with protein or fat slows digestion further. Anyone managing blood sugar closely should still track portions and follow their own clinician's guidance.

Is Watermelon Good for Weight Loss?

So is watermelon good for weight loss? The short answer is yes, when you respect the serving. Its calorie density is tiny, meaning you get a large volume of food for very few calories, which helps you feel full on a budget.

In a 2019 crossover trial, 33 adults who ate 2 cups of watermelon daily for four weeks lost body weight and felt fuller than when they ate calorie matched cookies.

Watermelon and Satiety

Researchers compared fresh watermelon against an equal calorie low fat cookie in overweight and obese adults. The watermelon weeks brought greater fullness, lower hunger, and drops in body weight, body mass index, and blood pressure. You can read the 2019 crossover trial for the full results.

The point is not that watermelon melts fat. Swapping a processed snack for whole fruit at the same calories can shift hunger and habits in your favor. The wider nutrient picture, from lycopene to potassium, only strengthens the case for whole fruit.

How to Log Watermelon Without Guessing

Logging fruit by eye is where diets quietly leak calories. A quick photo estimate keeps your diary honest, especially with soft foods like melon that resist a neat gram count. Snap the plate, confirm the cups, and let the numbers fill in.

For a fast check on any meal, the CalMeal app estimates calories and macros from a single photo. Pair that with your daily calorie needs and a free calorie counter to see exactly where watermelon fits.

Common Questions About Watermelon Calories

How many calories are in a whole watermelon?

A whole watermelon is mostly water but still large, so the total climbs quickly. At about 30 calories per 100 grams of flesh, several pounds of edible fruit can pass 1,000 calories. Portioning to one or two cups keeps a single sitting near 46 to 92 calories.

How many carbs in watermelon on a low carb diet?

One cup gives about 12 grams of carbs, most of it natural sugar. On a strict keto plan that can be a large share of a tight daily limit, so many low carb eaters keep watermelon to half a cup. On a moderate low carb approach, a full cup fits comfortably.

Does watermelon sugar content raise blood sugar fast?

The glycemic index is high, near 72 to 80, but the glycemic load of one cup is low at around 4 to 5. For most people a normal serving causes only a mild rise. Pair it with protein, like a slice of cheese, to blunt the response further.

When is the best time to eat watermelon for weight loss?

There is no magic hour, but a 150 gram serving before a meal can take the edge off hunger and trim what you eat next. It also works as a light dessert in place of ice cream. Consistency matters more than timing.

Watermelon proves you can eat something sweet and stay on track once you know the numbers. Start tracking your fruit and every other meal today, and take the guesswork out of calorie counting with AI powered food recognition. Get the app here: iOS or Android.