Watermelon nutrition facts: 100 g of raw watermelon has about 30 calories, 7.6 g of carbohydrate (6.2 g of it sugars), 0.4 g of fibre, 112 mg of potassium and 8.1 mg of vitamin C. It is about 91.5% water.
That makes watermelon a light, hydrating fruit. However, it is not a rich source of vitamin A or fibre, despite common claims.
What Is Watermelon?
Watermelon is a sweet summer fruit with red flesh, a green rind and black or white seeds. Most of its weight is water. The red colour comes from lycopene.
Watermelon Nutrition Facts per 100 g, Cup and Serving
The table uses one USDA entry: raw watermelon. The cup column is calculated from the per 100 g values for a cup of diced fruit of about 152 g. Percent Daily Value (%DV) uses current FDA reference amounts.
| Nutrient | Per 100 g | 1 cup diced (about 152 g) | %DV (cup) | Serving (280 g) | %DV (280 g) |
|---|---|---|---|---|---|
| Calories | 30 | 46 | n/a | 84 | n/a |
| Protein | 0.6 g | 0.9 g | n/a | 1.7 g | n/a |
| Total fat | 0.15 g | 0.2 g | 0% | 0.4 g | 1% |
| Carbohydrate | 7.6 g | 11.5 g | 4% | 21.1 g | 8% |
| Total sugars | 6.2 g | 9.4 g | n/a | 17.4 g | n/a |
| Fibre | 0.4 g | 0.6 g | 2% | 1.1 g | 4% |
| Sodium | 1 mg | 1.5 mg | 0% | 2.8 mg | 0% |
| Potassium | 112 mg | 170 mg | 4% | 314 mg | 7% |
| Vitamin C | 8.1 mg | 12.3 mg | n/a | 22.7 mg | n/a |
| Vitamin A (RAE) | 28 mcg | 43 mcg | 5% | 78 mcg | 9% |
| Lycopene | 4,532 mcg | 6,889 mcg | n/a | 12,690 mcg | n/a |
Why Watermelon Nutrition Facts Differ Between Sources
Pages quote 30, 46, 80 and 84 calories for watermelon. All can be correct.
- Serving size. Thirty calories is per 100 g. Forty-six is about one cup diced. Eighty-four is the 280 g serving used on US labels. Doubling a cup gives 92 calories, not the 86 some pages print.
- Rounding. The label summary rounds the 280 g serving from 84 to 80 calories.
- The 4/4/9 shortcut. Protein, carbohydrate and fat multiplied by 4, 4 and 9 give about 34 calories per 100 g, not 30. USDA likely applies food-specific energy factors, so the shortcut overshoots for fruit.
- Cup weight. Cup values depend on how finely the fruit is diced and packed. The 152 g cup used here is implied by common per cup figures, not stated by the source.
Therefore, compare per 100 g when you check two sources.
Lycopene, Vitamins and Potassium in Watermelon
Lycopene. Watermelon holds 4,532 mcg per 100 g. This pigment is an antioxidant. No Daily Value exists for it.
Vitamin C. A 280 g serving supplies about 22.7 mg. That is useful, but many other fruits supply more.
Vitamin A. A 280 g serving supplies 78 mcg RAE, or about 9% of the Daily Value. Watermelon is not a rich source.
Potassium and fibre. A 280 g serving gives 7% of the potassium Daily Value and 4% of the fibre Daily Value.
Citrulline. Watermelon also contains the amino acid citrulline. Research on blood pressure mostly tests supplements, extracts or juice, so it does not prove that eating slices lowers blood pressure.
What the Evidence Says About Watermelon Claims
| Claim | Where it stands | What to know |
|---|---|---|
| Watermelon is hydrating | Supported | About 91.5% water by weight. |
| Watermelon is high in lycopene | Supported | 4,532 mcg per 100 g in USDA data. |
| Watermelon is a rich source of vitamin A | Not supported | About 9% of the Daily Value per 280 g. |
| Watermelon lowers blood pressure | Overstated | Trials test citrulline supplements, extract or juice. Fruit alone is not shown to treat hypertension. |
| Watermelon improves digestion | Overstated | Only 0.4 g of fibre per 100 g. Water adds volume, not fibre. |
| Watermelon reduces wrinkles or spots | Not supported | No evidence from eating the fruit. |
| Watermelon boosts metabolic rate | Not supported | No food does this. |
| Eating watermelon daily harms the kidneys | Not supported | Potassium is modest. People on potassium limits should still ask their care team. |
Watermelon Safety: Sugar, Potassium and Medication
Medication. Never stop or swap prescribed blood pressure medicine for watermelon. Talk to your prescriber first.
Diabetes. A 280 g serving holds about 21 g of carbohydrate and 17 g of sugars. Ask your care team how to count it.
Potassium limits. People told to limit potassium, for example with kidney disease, should ask how much fits. A 280 g serving holds 7% of the Daily Value.
US and UK labels. US labels show per serving values and %DV. UK labels usually show per 100 g, so the per 100 g column above is the easiest to compare.
Watermelon Nutrition Facts FAQ
About 30 calories per 100 g, 46 per cup of diced fruit and 84 per 280 g serving, based on USDA data for raw watermelon.
About 6.2 g per 100 g, 9.4 g per cup diced and 17.4 g per 280 g serving. These are natural sugars within the fruit.
Yes. USDA lists 4,532 mcg of lycopene per 100 g. Lycopene is the pigment that makes the flesh red.
Not especially. A 280 g serving gives about 78 mcg RAE of vitamin A, roughly 9% of the Daily Value, and about 22.7 mg of vitamin C.
It can contribute. Watermelon is about 91.5% water by weight, so a large serving adds a useful amount of fluid.
Not proven. Studies mostly test citrulline supplements, extract or juice. Do not replace prescribed medicine with watermelon, and talk to your prescriber about blood pressure.
No single food causes weight loss. Watermelon is low in calories per 100 g, but portion size still sets the total. A registered dietitian can tailor advice to you.
Many can, within their care plan. A 280 g serving has about 21 g of carbohydrate, so portion size matters. Ask your care team how to count it.
Pages use different serving sizes, such as 100 g, one cup or 280 g, and some round values. Compare per 100 g to check two sources fairly.
Related Reading
- Balance protein, carbs and fats
- Heart disease prevention: 10 preventive measures
- Kiwi fruit nutrition and side effects
- 15 foods and the immune system
Sources
- USDA FoodData Central, SR Legacy, raw watermelon, FDC 167765. Values read from a mirror: getfoodfacts.com
- FDA: Daily Value on the Nutrition and Supplement Facts Labels
- NIH Office of Dietary Supplements: Vitamin A and Carotenoids
- PubMed: L-citrulline supplementation and watermelon intake and blood pressure, systematic review and meta-analysis (title only; findings not reviewed here)
This article is for general information and is not medical or dietetic advice. Talk to your doctor or a registered dietitian about your own needs, especially if you manage diabetes, blood pressure or kidney disease.
Last reviewed and rewritten October 2026.
