Onion glycemic index
Onion has no measurable glycemic index: a 80 g serving (1 side portion) has only 6.1 g of available carbohydrate, so its glycemic load is about 0 and it barely raises blood sugar on its own.
- Serving80 g
- Available carbs6.1 g
- Fiber1.4 g
- Sugars3.4 g
- Protein0.9 g
- Calories32 kcal
Serving: 1 side portion.
What to know
Onions contain a little more carbohydrate than leafy vegetables, but in the amounts used for cooking their glycemic load is very small.
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Frequently asked questions
Does onion have a glycemic index?
Not a measurable one. GI can only be tested in foods with enough carbohydrate: the test needs a 25 or 50 g carbohydrate portion. Onion has 7.6 g per 100 g, so its direct effect on blood sugar is minimal and its glycemic load is about 0.
Does onion raise blood sugar?
Barely, on its own. What matters more is what you eat it with: bread, rice, potatoes, sauces or sugary drinks. Pairing carbohydrate foods with protein, fat or fiber tends to soften the rise.
How many carbs are in onion?
A 80 g serving has about 7.5 g of total carbohydrate, including 1.4 g of fiber, leaving 6.1 g of available carbohydrate (the part that raises blood sugar). Per 100 g: 9.3 g of carbohydrate.
Nutrition facts
| per 100 g | Serving (80 g) | |
|---|---|---|
| Calories | 40 kcal | 32 kcal |
| Carbohydrates | 9.3 g | 7.5 g |
| Available carbs | 7.6 g | 6.1 g |
| Fiber | 1.7 g | 1.4 g |
| Sugars | 4.2 g | 3.4 g |
| Protein | 1.1 g | 0.9 g |
| Fat | 0.1 g | 0.1 g |
Source: USDA FoodData Central, Onions, raw (SR Legacy, FDC 170000). 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.