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A baked red onion sits in layered wedges, its purple-red outer layers softened and lightly browned at the edges, with glossy, translucent rings visible inside.
●Low GI

Baked Red Onion Calories

Sweet, tender, antioxidant-rich

In season: Spring · Summer · Autumn · Winter

CALORIES · 100 G

44kcal

GI

35low

POTASSIUM · 100 G

146mg

FIBER · 100 G

1.7g

Quick answer

1 piece (medium) of Baked Red Onion (80 g) has 35 calories. That works out to 44 calories per 100 g. It contains 8.1 g of carbs, 0.9 g of protein, 0.1 g of fat and 1.4 g of fiber. Its 5.6 mg of Vitamin C covers 6% of the Daily Value. Its glycemic index is 35 (low), so it raises blood sugar slowly.

Baked Red Onion Nutrition Facts

Selected: 1 piece (medium) · 80 g

35

KCAL / 80G

Carbs

8.1g

· 3% DV

Protein

0.9g

· 2% DV

Fat

0.1g

· 0% DV

Fiber

1.4g

· 5% DV

DV is the share of the daily value covered, on a 2,000 kcal reference diet.

Calories come from: Carbs 88% · Protein 10% · Fat 2%

Baked Red Onion nutrition facts table · 1 piece (medium) (80 g)

NutrientAmount% DV
Calories35 kcal
Total fat0.1 g0%
Saturated fat0.02 g0%
Trans fat0 g
Sodium3.2 mg0%
Total carbohydrate8.1 g3%
Fiber1.4 g5%
Protein0.9 g2%

Calories: Calories measure energy. Average daily need is 2,000 kcal. Excess calories are stored as fat, too few cause weight loss.

Carbs: Your body's primary energy source. The brain runs exclusively on carbs. Daily need: 275g.

Protein: Essential for muscle repair and cell growth. Daily need: 50g. Keeps you full and boosts metabolism.

Fat: Needed for hormone production and vitamin absorption. Daily need: 78g. Limit saturated fats, choose unsaturated.

Fiber: Critical for digestive health and satiety. Daily need: 28g. Stabilizes blood sugar, lowers cholesterol.

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How Many Calories in 1 Medium Baked Red Onion?

ServingAmountCalories
1 piece (medium)80 g35 kcal
1 slice (thin)20 g9 kcal
1 slice (thick)35 g15 kcal
1 piece (small)50 g22 kcal
100 g100 g44 kcal
1 serving (medium)100 g44 kcal
1 piece (large)120 g53 kcal
1 serving (large)150 g66 kcal

Calculated from 44 calories per 100 g.

Frequently Asked Questions About Baked Red Onion

How do you make baked red onion?

To make baked red onion, peel it, cut it into wedges, and toss with olive oil, salt, and pepper. Roast in a hot oven until tender and browned at the edges, turning the pieces once for more even cooking.

Can you bake a red onion whole?

Yes, you can bake a red onion whole. Leave the papery skin on to help protect the inside, place it on a tray, and roast until a knife passes through easily; peel it before serving.

Why is my baked red onion still sharp or bitter?

Baked red onion can taste sharp if it has not cooked long enough to soften and mellow. Cut thick wedges into smaller pieces and continue roasting until tender; very dark, scorched edges can also make the flavor bitter.

Should you cover baked red onion with foil?

No, leave baked red onion uncovered if you want browned, caramelized edges. Foil traps steam, which softens the onion but prevents much browning; cover it only if you are deliberately aiming for a softer, steamed texture.

Can you make baked red onion in an air fryer?

Yes, baked red onion works well in an air fryer. Cut it into evenly sized wedges, coat lightly with oil, and cook in a single layer, shaking the basket once so the pieces brown without overcrowding.

What herbs and seasonings go with baked red onion?

Baked red onion pairs well with thyme, rosemary, oregano, black pepper, and a little balsamic vinegar. Add fresh herbs after roasting so they stay fragrant, or use dried herbs before cooking to season the onion throughout.

How do you use baked red onion in a sandwich?

Let baked red onion cool slightly, then layer it into a sandwich with cheese, hummus, grilled vegetables, or sliced meat. Its soft texture and sweet, savory flavor work especially well with peppery greens and a tangy spread.

Can you freeze baked red onion?

Yes, baked red onion can be frozen in an airtight container, though it will be softer after thawing. Use thawed portions in sauces, soups, or cooked dishes rather than expecting them to keep their original roasted texture.

Does baking red onion reduce its antioxidants?

Baking red onion can reduce some heat-sensitive compounds, while its natural plant pigments and other beneficial compounds do not all disappear. Roasting also makes the onion tender and flavorful, so both raw and cooked onion can fit into meals.

Can you use baked red onion on pizza?

Yes, baked red onion is a good pizza topping. Roast it first if you want a soft, sweet result, then add it before the pizza goes into the oven; this helps prevent the onion from releasing excess moisture onto the crust.

Baked Red Onion Vitamins & Minerals

Vitamins

Vitamin C

5.6mg · 6% DV

B6

0.1mg · 6% DV

Folate

15.2µg · 4% DV

B1

0.04mg · 3% DV

Minerals

Manganese

0.1mg · 4% DV

Copper

0.03mg · 3% DV

Potassium ⭐

117mg · 3% DV

Phosphorus

23mg · 3% DV

Sodium

3.2mg · 0% DV

Baked Red Onion Glycemic Index

GLYCEMIC INDEX

35
Low
0 Low5570100

GLYCEMIC LOAD

3.2
Low

Accounts for portion size — a more realistic measure than GI alone.

How to Burn Off Baked Red Onion

To burn the 35 calories in 1 piece (medium) (80 g):

🚶

9min

Walking (5 km/h)

🏃

4min

Running (8 km/h)

🚴

5min

Cycling

🏊

4min

Swimming

Times are calculated with the MET equation for a 70 kg adult. Actual burn varies with your weight, age and pace.

What is Baked Red Onion?

Baked red onion is made by roasting red onions until their layers turn soft and sweet. You can bake them whole, halved or in wedges, with a little oil and herbs if you like. It is a simple home-cooking preparation rather than a dish tied to one particular region, and versions appear in many cuisines.

Roasting mellows the onion’s sharpness and brings out a tender centre with lightly browned edges. Serve it alongside grilled meat or fish, fold it into salads, or add it to a tray of other roasted vegetables. It is mostly a carbohydrate source, with very little fat; a 100 g portion provides 44 calories. For a lighter result, use just enough oil to coat the onion, or roast it on baking paper.

How Nutritious Is Baked Red Onion?

Nutrient density

Medium

55/ 100

How many vitamins, minerals and how much fiber this food carries per calorie. A high score means a lot of nutrition for few calories.

Satiety score

Medium

46/ 100

An EatBetter score computed from fiber, protein and calorie density. A high score means staying full longer on the same calories.

Both scores are calculated per 100 g and do not change with the selected portion. The satiety score is EatBetter's own calculation, not a clinical measure.

Is Baked Red Onion Processed?

NOVA 2

Minimally Processed

1. Unprocessed

2. Minimally Processed

3. Processed

4. Ultra-Processed

NOVA classifies foods into 4 groups by industrial processing. NOVA 1 (unprocessed) is the healthiest.

Does Baked Red Onion Contain Allergens?

No known major allergens

Gluten free
Dairy free
Eggs free
Peanuts free
Tree nuts free
Fish free
Soy free
Sesame free

Which Diets Is Baked Red Onion Good For?

Vegan

✓ Suitable

Vegetarian

✓ Suitable

Gluten-Free

✓ Suitable

Dairy-Free

— Not suitable

Mediterranean

✓ Suitable

Paleo

✓ Suitable

Whole30

— Not suitable

DASH

— Not suitable

Keto

— Not suitable

Low FODMAP

— Not suitable

Baked Red Onion Fat Profile

SATURATED

0.02g

MONOUNSATURATED

0.01g

POLYUNSATURATED

0.02g

⚖️

Omega 6:3 ratio 2:1

Below the ideal 4:1 — a good omega balance.

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Nutrition data compiled from USDA FoodData Central and scientific sources.