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Onion nutrition facts

One medium (2-1/2" dia) (110 g) of onion has 44 calories, with 1.2 g protein, 10.3 g carbohydrate, 0.1 g fat.

Key nutrition

Nutrition in 1 medium (2-1/2" dia) of onion and per 100 g
Nutrient1 medium (2-1/2" dia) (110 g)Per 100 g% Daily Value
Calories44 kcal40 kcal—
Protein1.2 g1.1 g2%
Carbohydrate10 g9.3 g4%
Fibre1.9 g1.7 g7%
Sugars4.7 g4.2 g—
Fat0.11 g0.1 g0%
Saturated fat0.05 g0.04 g0%
Sodium4.4 mg4 mg0%
Potassium161 mg146 mg3%
Calcium25 mg23 mg2%
Iron0.23 mg0.21 mg1%
Vitamin C8.1 mg7.4 mg9%

Values are from the USDA FoodData Central database. The tool above shows every vitamin, mineral, fat and amino acid, and any portion you like.

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Frequently asked questions

How many calories are in onion?
One medium (2-1/2" dia) (110 g) of onion has about 44 calories. Per 100 g that is 40 calories. The figures are from the USDA FoodData Central database (lab-measured values).
How much protein is in onion?
One medium (2-1/2" dia) (110 g) has 1.2 g of protein (1.1 g per 100 g). It is not a significant source of protein.
How many carbs are in onion?
One medium (2-1/2" dia) (110 g) has 10.3 g of carbohydrate, of which 1.9 g is fibre and 4.7 g is sugars.
Where do these onion nutrition numbers come from?
They come from the USDA FoodData Central database (SR Legacy), which is public domain, scaled to the portion shown. Brands and recipes vary, so treat them as typical values. Nothing you look up here is sent to a server.

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