A typical serving of onion (1 medium onion, 110 g) has about 44 calories. Per 100 g: 40 kcal, 1.1 g protein, 9.3 g carbs, 0.1 g fat. The same 100 g carries 1.7 g of fiber and 4.2 g of sugar. Most of the energy comes from carbohydrate.
| Serving | Weight | Calories |
|---|---|---|
| 1 medium onion | 110 g | 44 kcal |
| 1 large onion | 150 g | 60 kcal |
| 1 slice, medium | 14 g | 6 kcal |
| 100 g | 100 g | 40 kcal |
You cry over an ingredient that adds barely 44 calories to the whole dish. On the energy-density scale, 40 kcal per 100 g puts onion at the very low end.
A typical serving (1 medium onion, 110 g) has about 44 calories, and 100 g has 40 kcal. Calories scale with weight, so double the portion means double the number.
There are 1.1 g of protein in 100 g of onion, which works out to about 1.2 g per serving (1 medium onion). Treat it as an energy source rather than a protein source.
There are 9.3 g of carbohydrate per 100 g of onion, or about 10 g in 1 medium onion (110 g).
Every value on this page comes from USDA FoodData Central, entry 170000 (SR Legacy). Serving figures are converted from the per-100-g data, so rounding can shift a total by a calorie or two.
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Get JoulesA note on accuracy: calculators like this one provide estimates based on population-level formulas — your real needs vary with genetics, muscle mass, medical conditions, and more. Results are for information only and are not medical advice, a diagnosis, or a prescription. Talk to a doctor or registered dietitian before making significant changes to your diet or exercise, especially if you have a health condition, are pregnant, or are under 18.
Nutrition data: USDA FoodData Central, FDC ID 170000 (SR Legacy). Serving calories are computed from the per-100-g values.
