How many calories are in a slice of watermelon?

A large slice of about 280 g has around 85 kcal.

Is watermelon high in sugar?

It has about 6 g of natural sugar per 100 g, which is lower than most fruit.

Calories in watermelon

Watermelon has about 30 kcal per 100 g, so even a large slice is under 90 kcal.

By the Calori team · Updated 21 October 2026 · 3 min read

Watermelon calories by portion

Portion	Calories	Protein	Carbs	Fat
Portion (150 g)	45 kcal	0.9 g	10.8 g	0.3 g
Large slice (280 g)	84 kcal	1.7 g	20.2 g	0.6 g

Watermelon nutrition per 100 g

Energy	30 kcal (126 kJ)
Protein	0.6 g
Carbohydrate	7.2 g
of which sugars	6.2 g
Fat	0.2 g
Fibre	0.4 g

Typical values. Carbohydrate excludes fibre, as on UK food labels. Brands and varieties differ, so check the label where there is one.

Watermelon and hunger

Watermelon is over 90% water, so it fills you up for very few calories. It is low in protein and fibre, so it will not keep you full for long on its own.

Log it without looking it up

Calori recognises foods like this from a photo and estimates the portion, so you can log a whole plate in one go. Set your daily target with our calorie calculator.

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Frequently asked questions

How many calories are in a slice of watermelon?: A large slice of about 280 g has around 85 kcal.
Is watermelon high in sugar?: It has about 6 g of natural sugar per 100 g, which is lower than most fruit.