Watermelon glycemic index
Watermelon has a glycemic index of 50, which is low. A 120 g serving (1 cup diced) has a glycemic load of 4 (low).
Also known as: water melon
- Serving120 g
- Available carbs8.5 g
- Fiber0.5 g
- Sugars7.4 g
- Protein0.7 g
- Calories36 kcal
Serving: 1 cup diced.
What to know
Watermelon is often called high GI because of older tests around 72–80, but newer ISO-method studies average about 50. Either way it is mostly water, so a normal slice has a very low glycemic load.
Glycemic load by portion size
GI stays the same whatever you eat, but glycemic load scales with the amount: eating twice as much doubles the effect on blood sugar.
| Amount | Available carbs | Glycemic load | |
|---|---|---|---|
| 50 g | 3.6 g | 2 | Low |
| 100 g | 7.1 g | 4 | Low |
| 120 g · 1 cup diced | 8.5 g | 4 | Low |
| 240 g · double serving | 17 g | 9 | Low |
What the studies found
The value of 50 is the mean calculated by the authors of the International Tables of Glycemic Index (2021) across 8 studies. Results range from 47 to 80. That spread is normal: GI changes with variety, ripeness, cooking and processing, and between labs.
Each dot is one study. Green dots followed the ISO 26642 standard method.
- 47 · Malaysia 2017
- 48 · Malaysia 2017
- 50 · Jamaica 2019
- 51 · Malaysia 2017
- 51 · Malaysia 2017
- 55 · Malaysia 2008
- 72 · Australia 1994
- 80 · Australia 2003
Watermelon compared with other fruits
Similar low-GI foods
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Frequently asked questions
Is watermelon low glycemic?
Yes. With a GI of 50, watermelon is in the low range (55 or less).
What is the glycemic load of watermelon?
A 120 g serving (1 cup diced) has a glycemic load of 4, which is low. Glycemic load combines GI with the amount of carbohydrate in the portion: 10 or less is low, 11 to 19 medium and 20 or more high.
Can people with diabetes eat watermelon?
With a GI of 50 and a low glycemic load per serving, watermelon usually fits a diabetes-friendly diet in normal portions. Everyone responds differently, so talk to your doctor or dietitian about your plan.
How many carbs are in watermelon?
A 120 g serving has about 9.1 g of total carbohydrate, including 0.5 g of fiber, leaving 8.5 g of available carbohydrate (the part that raises blood sugar). Per 100 g: 7.6 g of carbohydrate.
Nutrition facts
| per 100 g | Serving (120 g) | |
|---|---|---|
| Calories | 30 kcal | 36 kcal |
| Carbohydrates | 7.6 g | 9.1 g |
| Available carbs | 7.1 g | 8.5 g |
| Fiber | 0.4 g | 0.5 g |
| Sugars | 6.2 g | 7.4 g |
| Protein | 0.6 g | 0.7 g |
| Fat | 0.2 g | 0.2 g |
Source: USDA FoodData Central, Watermelon, raw (SR Legacy, FDC 167765). Available carbohydrate = total carbohydrate minus fiber.
Sources: Atkinson FS, Brand-Miller JC, Foster-Powell K, Buyken AE, Goletzke J. International tables of glycemic index and glycemic load values 2021: a systematic review. Am J Clin Nutr. 2021;114(5):1625–1632. USDA FoodData Central. How we calculate each value: Methodology & sources.
Data last reviewed 2026-09-29.