How many calories are in onion?

One 1 medium of onion (110 g) has about 44 calories. Per 100 g, onion has 40 calories.

How much protein is in onion?

A 1 medium serving of onion provides roughly 1.2 g of protein (1.1 g per 100 g).

What are the macros for onion?

Per 1 medium: 1.2 g protein, 9.9 g carbs and 0.1 g fat — that's roughly 11% protein, 87% carbs and 2% fat by calories.

How do I log onion without weighing it?

Take a photo of your plate in CalorieScan AI. The app recognises onion, estimates the portion, and returns calories and macros in about three seconds — then you can fine-tune it in plain English ("make that two servings").

Vegetables · Nutrition facts

🧅Calories in Onion

A 1 medium of onion (110 g) has 44 calories, with 1.2 g protein, 9.9 g carbs and 0.1 g fat.

Calories

Protein

1.2 g

Carbs

9.9 g

Fat

0.1 g

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Onion nutrition by serving size

Serving	Calories	Protein	Carbs	Fat
1 medium	44	1.2 g	9.9 g	0.1 g
100 g	40	1.1 g	9 g	0.1 g
1 oz (28 g)	11	0.3 g	2.6 g	0 g
1 cup (≈225 g)	90	2.5 g	20.3 g	0.2 g
200 g	80	2.2 g	18 g	0.2 g

Values are approximate, rounded from USDA FoodData Central and OpenFoodFacts references. Real plates vary — that's exactly why CalorieScan AI lets you correct any estimate in plain English.

Macro breakdown

Protein 11%Carbs 87%Fat 2%

Per 100 g: 40 cal
Per 1 oz: 11 cal
Fiber: 1.7 g / 100 g
Sugar: 4.2 g / 100 g

Compare

Onion vs other vegetables

Onion vs Carrot Onion vs Brussels Sprouts Onion vs Beets Onion vs Butternut Squash Onion vs Broccoli Onion vs Kale

Frequently asked

How many calories are in onion?
One 1 medium of onion (110 g) has about 44 calories. Per 100 g, onion has 40 calories.
How much protein is in onion?
A 1 medium serving of onion provides roughly 1.2 g of protein (1.1 g per 100 g).
What are the macros for onion?
Per 1 medium: 1.2 g protein, 9.9 g carbs and 0.1 g fat — that's roughly 11% protein, 87% carbs and 2% fat by calories.
How do I log onion without weighing it?
Take a photo of your plate in CalorieScan AI. The app recognises onion, estimates the portion, and returns calories and macros in about three seconds — then you can fine-tune it in plain English ("make that two servings").

More vegetables

🥕 Carrot 🥬 Brussels Sprouts 🫜 Beets 🎃 Butternut Squash 🥦 Broccoli 🥬 Kale 🫑 Bell Pepper 🫛 Green Beans

Stop looking up calories.

Snap a photo of onion — or any meal — and CalorieScan AI does the math. Free on iPhone.

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