Calories in raw onions.
40 kcal per 100 g.
Onions, raw · SR Legacy (2018-04) · USDA FDC 170000
Nutrition for your portion
| Nutrient | Per 100 g | 100 g |
|---|---|---|
| Energy | 40 kcal | 40 kcal |
| Protein | 1.1 g | 1.1 g |
| Carbohydrates | 9.34 g | 9.34 g |
| Fat | 0.1 g | 0.1 g |
| Fibre | 1.7 g | 1.7 g |
| Sugars | 4.24 g | 4.24 g |
| Saturated fat | 0.04 g | 0.04 g |
| Sodium | 4 mg | 4 mg |
| Salt (calculated from sodium) | 0.01 g | 0.01 g |
| Vitamin A (RAE) | 0 ug | 0 ug |
| Vitamin D (D2 + D3) | 0 ug | 0 ug |
| Vitamin E (alpha-tocopherol) | 0.02 mg | 0.02 mg |
| Vitamin K (phylloquinone) | 0.4 ug | 0.4 ug |
| Vitamin C | 7.4 mg | 7.4 mg |
| Thiamin | 0.05 mg | 0.05 mg |
| Riboflavin | 0.03 mg | 0.03 mg |
| Niacin | 0.12 mg | 0.12 mg |
| Vitamin B6 | 0.12 mg | 0.12 mg |
| Folate, total | 19 ug | 19 ug |
| Vitamin B12 | 0 ug | 0 ug |
| Potassium | 146 mg | 146 mg |
| Calcium | 23 mg | 23 mg |
| Phosphorus | 29 mg | 29 mg |
| Magnesium | 10 mg | 10 mg |
| Iron | 0.21 mg | 0.21 mg |
| Zinc | 0.17 mg | 0.17 mg |
| Selenium | 0.5 ug | 0.5 ug |
| Iodine | Unknown | Unknown |
| Copper | 0.04 mg | 0.04 mg |
Energy comes from USDA nutrient 1008. Salt is calculated as sodium × 2.5, with unit conversion to grams. It is not a separately measured salt value.
Preparation
Raw onions are 40 kcal per 100 g and nearly all of it carbohydrate. Frying is what changes them: the sugars caramelise, the water leaves, and the volume collapses to a fraction — but the calories that arrive on the plate are the onion's 40 per 100 g plus every gram of the oil or butter they were softened in, and that fat is usually several times the onion.
Logging this food
A tablespoon chopped is 10 g and 4 kcal, a cup chopped 160 g and 64, a cup sliced 115 g and 46. Whole onions: large 150 g and 60 kcal, medium 110 g and 44, small 70 g and 28. A slice on a burger is 14 g and 6. Almost every one of these numbers is small enough to round away — the fat they are cooked in is not.
Swaps and alternatives
Nothing in this family needs swapping for an onion. What is worth swapping is the method: onions softened in a splash of stock or water instead of oil land at their own 40 kcal per 100 g rather than at three or four times it, and for most sauces the difference in the finished dish is small.