🥦 Vegetablesveganvegetariangluten free
🧅 Calories in Onions
A culinary staple rich in quercetin — a powerful anti-inflammatory antioxidant
Per 100g
40kcal
1.1g
Protein
9.3g
Carbs
0.1g
Fat
Calculate Your Serving
Full Nutrition Facts — Per 100g
| Nutrient | Per 100g | Per 1 medium onion (110g) |
|---|---|---|
| Calories | 40kcal | 44kcal |
| Protein | 1.1g | 1.2g |
| Total Carbs | 9.3g | 10.2g |
| — of which Sugar | 4.2g | 4.6g |
| Total Fat | 0.1g | 0.1g |
| Dietary Fibre | 1.7g | 1.9g |
| Sodium | 4mg | 4mg |
Macro Breakdown
Protein1.1g (4.4 kcal)
Carbohydrates9.3g (37.2 kcal)
Fat0.1g (0.9 kcal)
All values per 100g. Protein & carbs = 4 kcal/g · Fat = 9 kcal/g
Key Vitamins & Minerals
Iron0.2mg
1% of daily reference intake
Vitamin C7.4mg
9% of daily reference intake
Potassium146mg
4% of daily reference intake
✅ Key Nutrition Facts
- •Rich in quercetin — one of the most potent antioxidants
- •Contains FOS prebiotics — feeds beneficial gut bacteria
- •Sulphur compounds linked to heart health and immunity
- •Only 40 calories per 100g — negligible calorie impact in cooking
Calories by Serving Size
| Serving | Grams | Calories | Protein |
|---|---|---|---|
| 100g raw | 100g | 40 kcal | 1.1g |
| 1 medium onion (110g) | 110g | 44 kcal | 1.2g |
| Half onion (55g) | 55g | 22 kcal | 0.6g |
Frequently Asked Questions
How many calories in an onion?+
A medium raw onion (110g) contains approximately 44 calories. Per 100g, onions are 40 calories. Cooked onions are slightly more calorie-dense per weight as water evaporates, but the calorie content is unchanged.
Are raw or cooked onions healthier?+
Raw onions retain more quercetin and vitamin C. However, cooking makes them more digestible and brings out prebiotics. Both have health benefits — variety is ideal. Caramelised onions lose some nutrients but concentrate their natural sugars.
Compare with Similar Foods
Data source: USDA FoodData Central & peer-reviewed nutritional references. Values are averages — actual nutrient content varies by brand, preparation method, and growing conditions. Not medical advice.