Food calories · USDA data
Calories in an onion
44 calories
in 1 medium (2-1/2" dia), 110 g
- Protein
- 1.2 g
- Carbs
- 10.3 g
- Fat
- 0.1 g
- Fiber
- 1.9 g
An onion has 44 calories. That is USDA's figure for 1 medium (2-1/2" dia), which weighs 110 g. Per 100 g, onion has 40 calories.
Almost all of its calories, 88%, come from carbohydrate.
It takes 250 g of onion to reach 100 calories, which is about 2.3 × 1 medium (2-1/2" dia).
Calories by portion
| Portion | Weight | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|---|
| 1 medium (2-1/2" dia) | 110 g | 44 | 1.2 g | 10.3 g | 0.1 g |
| 1 cup, chopped | 160 g | 64 | 1.8 g | 14.9 g | 0.2 g |
| 1 cup, sliced | 115 g | 46 | 1.3 g | 10.7 g | 0.1 g |
| 1 tbsp chopped | 10 g | 4 | 0.1 g | 0.9 g | 0 g |
| 1 large | 150 g | 60 | 1.7 g | 14 g | 0.2 g |
| 1 oz | 28.3 g | 11 | 0.3 g | 2.6 g | 0 g |
| 100 g | 100 g | 40 | 1.1 g | 9.3 g | 0.1 g |
Portion weights are USDA's own. Your onion may weigh more or less; for an exact number, weigh it and enter the grams in the food calorie lookup.
Where the calories come from
- Protein: 10% of calories (1.1 g per 100 g)
- Carbohydrate: 88% (9.3 g per 100 g, of which 1.7 g fiber)
- Fat: 2% (0.1 g per 100 g)
Shares use the general factors of 4 calories per gram of protein and carbohydrate and 9 per gram of fat, so they can differ a little from USDA's calorie figure. Daily Values are the FDA's adult Daily Values.
Compared with similar foods
Weight for weight, onion has the fewest calories of these four (40 per 100 g) and brussels sprouts the most (43).
| Per 100 g | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| Onion | 40 | 1.1 g | 9.3 g | 0.1 g |
| Carrot | 41 | 0.9 g | 9.6 g | 0.2 g |
| Beets | 43 | 1.6 g | 9.6 g | 0.2 g |
| Brussels sprouts | 43 | 3.4 g | 9 g | 0.3 g |
Work out your own portion
The food calorie lookup has 3,070 foods. Pick a portion or type a weight in grams or ounces, then add foods to a plate to see the total for a meal. To see how a meal fits your day, the calorie calculator works out your daily calories.
Questions people ask
How many calories is in an onion?
An onion has 44 calories. USDA weighs 1 medium (2-1/2" dia) at 110 g, and onion has 40 calories per 100 g.
How much protein does an onion have?
1 medium (2-1/2" dia) (110 g) has 1.2 g of protein, 2% of the 50 g Daily Value. Per 100 g it is 1.1 g.
How many carbs does an onion have?
1 medium (2-1/2" dia) has 10.3 g of carbohydrate, including 1.9 g of fiber, and 0.1 g of fat.
Source: USDA FoodData Central, SR Legacy (2018). USDA entry: Onions, raw (FDC ID 170000). Values are averages; a packaged food's label may differ.