Onion nutrition facts

Onion (1 medium (2-1/2" dia), 110 g) has 44 calories, 1.2 g protein, 1.9 g fiber, 0.1 g fat. No single vitamin or mineral reaches 10% of the Daily Value per serving.

Vitamin C 9% DV Vitamin B6 7.8% DV Fiber 6.7% DV Manganese 6.2% DV Folate 5.2% DV

Nutrition Facts

Serving size1 medium (2-1/2" dia) (110 g)

Calories44

Total Fat 0.1g0.1%

Saturated Fat 0g0.2%

Trans Fat 0g

Cholesterol 0mg0%

Sodium 4mg0.2%

Total Carbohydrate 10.3g3.7%

Dietary Fiber 1.9g6.7%

Total Sugars 4.7g

Protein 1.2g2.4%

Vitamin D 0µg0%

Calcium 25mg1.9%

Iron 0.2mg1.3%

Potassium 161mg3.4%

* The % Daily Value (DV) tells you how much a nutrient in a serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice. Values from USDA FoodData Central; label rounding rules are not applied.

Calorie breakdown

■ Protein 10%
■ Fat 2%
■ Carbohydrate 88%

Share of calories by the 4-9-4 Atwater factors; the centre shows USDA's calorie value.

Scores

Nutrient density (NRF9.3)

Nine nutrients to encourage minus three to limit, per 100 kcal. Whole foods range from about −60 to 600; leafy greens score highest.

0.4

Inflammatory profile anti-inflammatory

Lower is more anti-inflammatory. Percentile 28 among 1,677 whole foods, from Dietary Inflammatory Index weights applied to this food's nutrients per 100 kcal.

All nutrients in onion

Nutrient	Per 1 medium (2-1/2" dia)	% Daily Value
Macronutrients
Calories	44 kcal	2.2%
Protein	1.2 g	2.4%
Total fat	0.1 g	0.1%
Carbohydrate	10.3 g	3.7%
Fiber	1.9 g	6.7%
Sugars	4.7 g	no DV
Fats
Saturated fat	0 g	0.2%
Trans fat	0 g	no DV
Monounsaturated fat	0 g	no DV
Polyunsaturated fat	0 g	no DV
Omega-3 (ALA+EPA+DHA)	0 g	no DV
Omega-6 (linoleic)	0.01 g	no DV
Cholesterol	0 mg	0%
Vitamins
Vitamin C	8.1 mg	9%
Thiamin (B1)	0.05 mg	4.2%
Riboflavin (B2)	0.03 mg	2.3%
Niacin (B3)	0.1 mg	0.8%
Pantothenic acid (B5)	0.14 mg	2.7%
Vitamin B6	0.13 mg	7.8%
Folate (DFE)	21 µg	5.2%
Vitamin B12	0 µg	0%
Vitamin A (RAE)	0 µg	0%
Vitamin E	0.02 mg	0.1%
Vitamin D	0 µg	0%
Vitamin K	0.4 µg	0.4%
Choline	7 mg	1.2%
Minerals
Sodium	4 mg	0.2%
Calcium	25 mg	1.9%
Iron	0.2 mg	1.3%
Magnesium	11 mg	2.6%
Phosphorus	32 mg	2.6%
Potassium	161 mg	3.4%
Zinc	0.2 mg	1.7%
Copper	0.04 mg	4.8%
Manganese	0.14 mg	6.2%
Selenium	0.6 µg	1%
Carotenoids
Beta-carotene	1 µg	no DV
Lycopene	0 µg	no DV
Lutein + zeaxanthin	4 µg	no DV
Other
Caffeine	0 mg	no DV
Water	98 g	no DV
Amino acids
Tryptophan	0.015 g	no DV
Threonine	0.023 g	no DV
Isoleucine	0.015 g	no DV
Leucine	0.028 g	no DV
Lysine	0.043 g	no DV
Methionine	0.002 g	no DV
Phenylalanine	0.028 g	no DV
Valine	0.023 g	no DV
Histidine	0.015 g	no DV

Nutrient	Per 100 g	% Daily Value
Macronutrients
Calories	40 kcal	2%
Protein	1.1 g	2.2%
Total fat	0.1 g	0.1%
Carbohydrate	9.3 g	3.4%
Fiber	1.7 g	6.1%
Sugars	4.2 g	no DV
Fats
Saturated fat	0 g	0.2%
Trans fat	0 g	no DV
Monounsaturated fat	0 g	no DV
Polyunsaturated fat	0 g	no DV
Omega-3 (ALA+EPA+DHA)	0 g	no DV
Omega-6 (linoleic)	0.01 g	no DV
Cholesterol	0 mg	0%
Vitamins
Vitamin C	7.4 mg	8.2%
Thiamin (B1)	0.05 mg	3.8%
Riboflavin (B2)	0.03 mg	2.1%
Niacin (B3)	0.1 mg	0.7%
Pantothenic acid (B5)	0.12 mg	2.5%
Vitamin B6	0.12 mg	7.1%
Folate (DFE)	19 µg	4.8%
Vitamin B12	0 µg	0%
Vitamin A (RAE)	0 µg	0%
Vitamin E	0.02 mg	0.1%
Vitamin D	0 µg	0%
Vitamin K	0.4 µg	0.3%
Choline	6 mg	1.1%
Minerals
Sodium	4 mg	0.2%
Calcium	23 mg	1.8%
Iron	0.2 mg	1.2%
Magnesium	10 mg	2.4%
Phosphorus	29 mg	2.3%
Potassium	146 mg	3.1%
Zinc	0.2 mg	1.5%
Copper	0.04 mg	4.3%
Manganese	0.13 mg	5.6%
Selenium	0.5 µg	0.9%
Carotenoids
Beta-carotene	1 µg	no DV
Lycopene	0 µg	no DV
Lutein + zeaxanthin	4 µg	no DV
Other
Caffeine	0 mg	no DV
Water	89 g	no DV
Amino acids
Tryptophan	0.014 g	no DV
Threonine	0.021 g	no DV
Isoleucine	0.014 g	no DV
Leucine	0.025 g	no DV
Lysine	0.039 g	no DV
Methionine	0.002 g	no DV
Phenylalanine	0.025 g	no DV
Valine	0.021 g	no DV
Histidine	0.014 g	no DV

Nutrient	Per 1 oz (28 g)	% Daily Value
Macronutrients
Calories	11 kcal	0.6%
Protein	0.3 g	0.6%
Total fat	0 g	0%
Carbohydrate	2.6 g	1%
Fiber	0.5 g	1.7%
Sugars	1.2 g	no DV
Fats
Saturated fat	0 g	0.1%
Trans fat	0 g	no DV
Monounsaturated fat	0 g	no DV
Polyunsaturated fat	0 g	no DV
Omega-3 (ALA+EPA+DHA)	0 g	no DV
Omega-6 (linoleic)	0 g	no DV
Cholesterol	0 mg	0%
Vitamins
Vitamin C	2.1 mg	2.3%
Thiamin (B1)	0.01 mg	1.1%
Riboflavin (B2)	0.01 mg	0.6%
Niacin (B3)	0 mg	0.2%
Pantothenic acid (B5)	0.03 mg	0.7%
Vitamin B6	0.03 mg	2%
Folate (DFE)	5 µg	1.3%
Vitamin B12	0 µg	0%
Vitamin A (RAE)	0 µg	0%
Vitamin E	0.01 mg	0%
Vitamin D	0 µg	0%
Vitamin K	0.1 µg	0.1%
Choline	2 mg	0.3%
Minerals
Sodium	1 mg	0%
Calcium	7 mg	0.5%
Iron	0.1 mg	0.3%
Magnesium	3 mg	0.7%
Phosphorus	8 mg	0.7%
Potassium	41 mg	0.9%
Zinc	0 mg	0.4%
Copper	0.01 mg	1.2%
Manganese	0.04 mg	1.6%
Selenium	0.1 µg	0.3%
Carotenoids
Beta-carotene	0 µg	no DV
Lycopene	0 µg	no DV
Lutein + zeaxanthin	1 µg	no DV
Other
Caffeine	0 mg	no DV
Water	25 g	no DV
Amino acids
Tryptophan	0.004 g	no DV
Threonine	0.006 g	no DV
Isoleucine	0.004 g	no DV
Leucine	0.007 g	no DV
Lysine	0.011 g	no DV
Methionine	0.001 g	no DV
Phenylalanine	0.007 g	no DV
Valine	0.006 g	no DV
Histidine	0.004 g	no DV

Missing nutrients were not analysed by USDA for this food; they are not zero. F marks a value updated from Foundation Foods (April 2026 analytical data). Source: USDA FoodData Central #170000 ("Onions, raw").

Onion variants compared

Per 100 g, so preparations can be compared directly.

Variant	kcal	Protein g	Fat g	Carbs g	Fiber g	Sugars g	Potassium mg	Vit C mg	Sodium mg
Onion (this page)	40	1.1	0.1	9.3	1.7	4.2	146	7.4	4
Cooked	44	1.4	0.2	10.2	1.4	4.7	166	5.2	3

Frequently asked questions

How many calories are in onion?

Onion has 44 calories per 1 medium (2-1/2" dia) (110 g), or 40 calories per 100 g, according to USDA FoodData Central.

How much protein is in onion?

1.2 g of protein per 1 medium (2-1/2" dia), which is 2.4% of the 50 g Daily Value.

What is onion rich in?

Per serving, onion is richest in Vitamin C at 9% of the Daily Value, Vitamin B6 (7.8%), Fiber (6.7%), Manganese (6.2%).

Is onion healthy?

By nutrient density, onion scores 40 on the NRF9.3 index (nine nutrients to encourage minus three to limit, per 100 kcal). Its nutrient profile is anti-inflammatory compared with other whole foods. See the methodology page for how both scores work; this is data, not medical advice.

More vegetables

Nutrient values are from USDA FoodData Central (SR Legacy, April 2018; Foundation Foods, April 2026) and shown per serving as described on each page. %DV uses the FDA Daily Values for adults and children aged 4 and over. This is nutrition data for general information, not medical or dietary advice; talk to a clinician or registered dietitian about your own needs. How the numbers are calculated.