Calories in Onion
100 g of Onion has about 40 calories. At the reference weight of 110 g, that is about 44 calories. Enter the amount you actually eat to calculate your portion.
Calories per 100 g
40 kcal
calories per 100 g
- Protein
- 1.1 g
- Fat
- 0.1 g
- Carbs
- 9.3 g
These are reference values. Ingredients and preparation can change the result.
Macros in OnionCalculate calories for your portion
Enter the weight to calculate calories and macros here. No sign-up required.
In your portion
44 kcal
- Protein
- 1.2 g
- Fat
- 0.1 g
- Carbs
- 10.2 g
How to calculate calories in Onion
Multiply the calories per 100 g by your portion weight, then divide by 100. For the reference 110 g portion, the calculation is:
40 × 110 ÷ 100 ≈ 44 kcal
Reference portion: medium (110 g). This is an example amount, not a recommended portion. Weigh your food when possible: a cup, slice or piece can vary in size.
Check that the entry matches the food you have, including its preparation. If raw or cooked is not specified, check your label or a matching nutrition reference before logging it.
Calories by portion size
| Portion | Calories | Protein | Fat | Carbs |
|---|---|---|---|---|
| 50 g | 20 kcal | 0.6 g | 0.1 g | 4.7 g |
| 100 g | 40 kcal | 1.1 g | 0.1 g | 9.3 g |
| 110 g | 44 kcal | 1.2 g | 0.1 g | 10.2 g |
| 200 g | 80 kcal | 2.2 g | 0.2 g | 18.6 g |
Additional nutrients · 100 g
- Fiber
- 1.7 g
- Sugars
- 5 g
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How FoodWarz works →What changes the calories?
Oil, sauces, sugar, toppings, cooking method and portion weight can change onion calories quickly.
FAQ
How many calories are in a 110 g portion of Onion?
Using this reference entry, 110 g has about 44 calories. The calculator scales the per-100 g value; it does not identify your recipe or brand.
Can I use the same number for any cup, slice or piece?
No. Household measures and individual pieces can have different weights. Use the gram weight of the edible portion, or the serving weight printed on your package.
Is onion good for calorie tracking?
Yes, as long as you track portion size. The biggest source of error is usually weight, sauces, oil and mixed ingredients.
How Onion compares
Of the 6 other foods in this table, 3 have fewer calories per 100 g than Onion and 3 have more.
| Food | Calories | Protein | Fat | Carbs |
|---|---|---|---|---|
| Onion (this page) | 40 kcal | 1.1 g | 0.1 g | 9.3 g |
| GarlicMost calories | 149 kcal | 6.4 g | 0.5 g | 33 g |
| Mushrooms | 22 kcal | 3.1 g | 0.3 g | 3.3 g |
| AsparagusFewest calories | 20 kcal | 2.2 g | 0.1 g | 3.9 g |
| Green beans | 31 kcal | 1.8 g | 0.2 g | 7 g |
| Peas | 81 kcal | 5.4 g | 0.4 g | 14.5 g |
| Corn | 86 kcal | 3.3 g | 1.4 g | 19 g |
Data sources
Reference values are compiled from USDA FoodData Central, Open Food Facts and curated food databases. Your actual portion may differ by recipe, brand and cooking method.
Nutrition data methodologyNutrition values are estimates for calorie tracking and may vary by recipe, brand, cooking method and portion size. Not medical advice.
Last updated: October 3, 2026