Watermelon is very low in calories: about 30 calories per 100 grams of fresh watermelon, which is roughly 2/3 of a cup of cubes.

Quick Scoop: Calorie Basics

  • Around 30 kcal per 100 g of raw watermelon.
  • That’s about 45 calories per 1 cup of diced watermelon (≈150 g).
  • A typical large slice (around 280 g) has roughly 80–90 calories.

Because watermelon is over 90% water, its calorie density is much lower than most other sweet snacks or desserts.

Portion Examples

Think of it this way:

  1. Small snack (½ cup cubes): about 20–25 kcal.
  1. Standard bowl (1 cup cubes): about 45 kcal.
  1. Big slice (hand-sized wedge): roughly 80–90 kcal.

All of these are approximate because size, ripeness, and how you cut it can change the exact weight.

Why It’s Popular in Diets

  • High water content (around 91%) helps with hydration and a feeling of fullness.
  • Low fat and low protein , mostly carbs from natural sugars.
  • Contains vitamins and antioxidants like lycopene and vitamin C, so you get more than “empty” calories.

So if you’re watching your intake, watermelon is generally a very light choice compared with pastries, chocolate, or ice cream of the same volume.

Mini FAQ

  • Is watermelon “free” on a diet?
    Not literally, but its calorie content is low enough that moderate portions fit easily into most calorie budgets.
  • Does it have a lot of sugar?
    It has about 6 g of sugar per 100 g, which is similar to many fruits but with fewer calories thanks to the high water content.

TL;DR: If you’re eating a normal bowl or slice, you’re usually in the 20–90 calorie range depending on portion size, with ~30 kcal per 100 g as the key reference.

Information gathered from public forums or data available on the internet and portrayed here.