News of Health / Nutrition Facts Library
Onion Nutrition Facts: Is Onion Good for You?
Raw onions are very low in calories, fat, and sodium, making them a useful ingredient for adding flavor. While not a “high” source of any single nutrient by FDA standards, a 100-gram serving provides small amounts of Vitamin C (8% of the Daily Value), Vitamin B6 (7% DV), and manganese (6% DV). Whether an onion is good for you depends on your overall diet, but it can certainly be part of a balanced eating plan.
Per 100 g · Onions, raw
What stands out in onion
- Low in calories. A 100-gram serving of raw onion, which is slightly less than one medium onion, contains 40 calories. This makes it a low-calorie way to add flavor to meals.
- A source of vitamin C. Raw onions provide 7.4 mg of Vitamin C per 100 grams. This amount supplies 8% of the recommended Daily Value.
- Provides B vitamins and minerals. A 100-gram portion of raw onion contains several B vitamins and minerals in small amounts, including 7% of the DV for Vitamin B6, 6% for manganese, and 5% for folate.
- Almost no fat or sodium. Onions are naturally very low in fat and sodium. A 100-gram serving contains just 0.1 grams of total fat and 4 mg of sodium.
What to keep in mind
- Raw onions are very low in nutrients that people often limit, including calories, saturated fat, and sodium. They contain 4.2 grams of total sugars per 100-gram serving.
Onion nutrition facts per 100 g
| Nutrient | Per 100 g | % DV |
|---|---|---|
| Calories | 40 kcal | – |
| Protein | 1.1 g | 2% |
| Total fat | 0.1 g | 0% |
| Saturated fat | 0.04 g | 0% |
| Monounsaturated fat | 0.01 g | – |
| Polyunsaturated fat | 0.02 g | – |
| Cholesterol | 0 mg | 0% |
| Carbohydrate | 9.3 g | 3% |
| Dietary fiber | 1.7 g | 6% |
| Total sugars | 4.2 g | – |
| Water | 89.1 g | – |
| Sodium | 4 mg | 0% |
| Nutrient | Per 100 g | % DV |
|---|---|---|
| Potassium | 146 mg | 3% |
| Calcium | 23 mg | 2% |
| Iron | 0.21 mg | 1% |
| Magnesium | 10 mg | 2% |
| Phosphorus | 29 mg | 2% |
| Zinc | 0.17 mg | 2% |
| Copper | 0.04 mg | 4% |
| Manganese | 0.13 mg | 6% |
| Selenium | 0.5 mcg | 1% |
| Vitamin A (RAE) | 0 mcg | 0% |
| Vitamin C | 7.4 mg | 8% |
| Vitamin D | 0 mcg | 0% |
| Vitamin E | 0.02 mg | 0% |
| Vitamin K | 0.4 mcg | 0% |
| Thiamin (B1) | 0.05 mg | 4% |
| Riboflavin (B2) | 0.03 mg | 2% |
| Niacin (B3) | 0.12 mg | 1% |
| Vitamin B6 | 0.12 mg | 7% |
| Folate (DFE) | 19 mcg | 5% |
| Vitamin B12 | 0 mcg | 0% |
| Choline | 6.1 mg | 1% |
% Daily Value uses the FDA Daily Values for adults and children 4 years and older. Highlighted rows are 20% DV or more per 100 g. A dash means no Daily Value is set.
Onion by portion
The nutrition information changes with portion size. A large serving like “1 cup, chopped” (160 g) provides 64 calories, 14.9 grams of carbohydrates, and 2.7 grams of fiber. A “1 medium (2-1/2″ dia)” onion (110 g) has 44 calories and 4.6 grams of sugar. Smaller amounts contribute less; for example, “1 tbsp chopped” (10 g) contains just 4 calories and 0.4 grams of sugar.
| USDA portion | Weight | Calories | Protein | Carbs | Fiber | Fat |
|---|---|---|---|---|---|---|
| 1 cup, chopped | 160 g | 64 | 1.8 g | 14.9 g | 2.7 g | 0.2 g |
| 1 cup, sliced | 115 g | 46 | 1.3 g | 10.7 g | 2 g | 0.1 g |
| 1 tbsp chopped | 10 g | 4 | 0.1 g | 0.9 g | 0.2 g | 0 g |
| 1 large | 150 g | 60 | 1.7 g | 14 g | 2.5 g | 0.2 g |
| 1 slice, large (1/4″ thick) | 38 g | 15 | 0.4 g | 3.5 g | 0.6 g | 0 g |
| 1 medium (2-1/2″ dia) | 110 g | 44 | 1.2 g | 10.2 g | 1.9 g | 0.1 g |
How onion compares with other vegetables
Compared to the 37 other vegetables in this data set, raw onions are ranked in the top half for carbohydrates (13th) and total sugars (8th). They rank lower for their content of fiber (27th), potassium (36th), and iron (37th). Per 100 grams, the calorie count of onions (40 kcal) is very similar to other root vegetables like carrots (41 kcal), jicama (38 kcal), rutabaga (37 kcal), and beets (43 kcal). Based on the data provided, raw onions are not considered a “high source” or “good source” of any vitamin or mineral.
| Per 100 g | Calories | Protein | Carbs | Fiber | Fat |
|---|---|---|---|---|---|
| Onion | 40 | 1.1 g | 9.3 g | 1.7 g | 0.1 g |
| Carrots | 41 | 0.93 g | 9.6 g | 2.8 g | 0.24 g |
| Jicama | 38 | 0.72 g | 8.8 g | 4.9 g | 0.09 g |
| Rutabaga | 37 | 1.1 g | 8.6 g | 2.3 g | 0.16 g |
| Beets | 43 | 1.6 g | 9.6 g | 2.8 g | 0.17 g |
Quick answers
How many calories are in an onion?
A “1 medium (2-1/2″ dia)” raw onion weighing 110 grams has 44 calories. A “1 large” onion (150 g) contains 60 calories.
How much sugar and carbs are in an onion?
A medium raw onion (110 g) contains 10.2 grams of total carbohydrates, of which 4.6 grams are sugars. One cup of chopped onion (160 g) has 14.9 grams of carbohydrates and 6.7 grams of sugars.
Are onions a good source of fiber?
A medium raw onion provides 1.9 grams of dietary fiber, which is about 6% of the Daily Value per 100 grams. According to FDA labeling guidelines, this means it is not considered a “good source” of fiber, which requires at least 10% of the Daily Value.
When to talk to a doctor or dietitian
- This page describes nutrient content, not medical advice. If a health condition, medicine or pregnancy affects what you eat, a doctor or registered dietitian can tell you how onion fits your situation.
Last updated October 21, 2026