All Foods
Vegetables
Onion
40 kcal per 100g
Nutrition Facts
Serving size: 100g
Calories40
per serving
Total Fat0.1g
Total Carbohydrate9.3g
Dietary Fiber1.7g
Total Sugars4.2g
Protein1.1g
Sodium4mg
Health Info
Onions are low in calories and a notable source of quercetin, an antioxidant flavonoid, plus prebiotic fibers that feed gut bacteria. Their sulfur compounds — released when chopped — are being studied for cardiovascular benefits.
Macros per 100g
40kcal
Calories
1.1g
Protein
9.3g
Carbs
0.1g
Fat
Values per 100 g are based on recognised nutrition reference data. Last reviewed: June 2026. View sources
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Frequently Asked Questions
- How many calories are in Onion?
- Onion has 40 kcal per 100 g. A typical 110 g serving contains about 44 kcal.
- How much protein is in Onion?
- Onion provides 1.1 g of protein per 100 g.
- How many carbs are in Onion?
- Onion contains 9.3 g of carbohydrates per 100 g, of which 4.2 g is sugar.
- How much fat is in Onion?
- Onion contains 0.1 g of fat per 100 g. It also provides 1.7 g of fiber per 100 g.
- Is Onion good for weight loss?
- With only 40 kcal per 100 g, Onion is low in calories and fits easily into a weight-loss diet.