How many calories are in watermelon?

Watermelon is one of the lowest-calorie fruits available. Per 100g it provides just 33 kcal — almost all from natural sugars (7.1g). A large wedge (around 280g) contains approximately 92 kcal. This makes watermelon an excellent choice for volume eating — you get a lot of food for very few calories.

Is watermelon high in sugar?

Watermelon contains 7.1g of sugar per 100g, which is actually lower than many fruits — apples have around 10g, grapes around 16g, and bananas around 12g. Watermelon tastes very sweet because it is over 90% water, so the sugar you do taste is concentrated on your palate. The total sugar per serving is modest, and it is all naturally occurring fructose with no added sugars.

Does watermelon spike blood sugar?

Watermelon has a high glycaemic index (GI ~72), which sounds concerning. However, the glycaemic load (GL) per serving is only about 5, which is classified as low. This is because watermelon is mostly water with very few carbs per portion. You would need to eat roughly 700g of watermelon — nearly an entire mini watermelon — to match the blood sugar impact of two slices of white bread. In normal portions, watermelon is unlikely to cause a significant glucose spike.

Glucose: MediumNOVA 1

Nutritional Information for Watermelon

Watermelon is a hydrating, low-calorie fruit delivering just 30-33 kcal per 100g — over 90% of it is water. From a SpikeSaver perspective, watermelon has a misleadingly high GI of around 72, which often alarms people. But the glycaemic load (GL) per serving is actually low (~5 per 120g serving) because there are so few carbs per portion. You would need to eat nearly 700g of watermelon to match the glucose impact of two slices of white bread. This is a classic case where GI alone tells the wrong story.

Nutrition per 100g

Nutrient	Per 100g	Per serving
Energy	33 kcal / 141 kJ	92 kcal
Protein	0.5g	1.4g
Carbohydrates	7.1g	19.9g
of which sugars	7.1g	—
Fat	0.3g	0.8g
of which saturated	0.1g	—
Fibre	0.1g	—
Salt	0.01g	—

Serving size: 1 wedge (~280g) · Source: Tesco product page, October 2025

Glucose impact

Glycemic Index

Medium

Glucose risk

Watermelon has a high glycaemic index (~72) which looks alarming on paper. However, the actual glucose impact per serving is moderate to low because watermelon is over 90% water with only 7.1g of carbs per 100g. The glycaemic load per typical serving (~120g) is only around 5, which is classified as low. You would need to eat a very large quantity to cause a significant blood sugar spike. Pairing watermelon with nuts or cheese further blunts any glucose response.

Processing level

NOVA 1 (unprocessed)

Whole watermelon and pre-cut watermelon pieces (wedges, chunks, fingers) are NOVA 1 — just fresh fruit, minimally processed by cutting. There are no additives, preservatives, or flavourings. Fruit salad mixes containing watermelon alongside other fruits remain NOVA 1 as they are simply combined fresh ingredients.

Watermelon at Tesco

Source: Tesco product page, October 2025

Tesco Watermelon

£3.50*NOVA 1 (unprocessed)

Tesco Mini Watermelon

£2.30*NOVA 1 (unprocessed)

Tesco Watermelon Wedges 550G

£3.10*NOVA 1 (unprocessed)

Tesco Watermelon Chunks 300G

£2.50*NOVA 1 (unprocessed)

Tesco Watermelon Fingers 600G

£4.25*NOVA 1 (unprocessed)

*Prices were correct at the time of collection and may have since changed. Check Tesco.com for current pricing.

What to watch for when shopping

All plain watermelon products at Tesco are NOVA 1 — whole, mini, wedges, chunks, and fingers are all just fresh fruit. The mixed fruit pots (Watermelon Strawberry & Black Grape, Watermelon & Mango) are also NOVA 1 but have slightly higher sugar per 100g due to the sweeter companion fruits. From a glucose perspective, do not be scared by the high GI number — the glycaemic load per serving is low. Budget tip: Tesco Mini Watermelon at £2.30 is the best value for a whole fruit.

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