Onion Nutrition Facts
Complete onion nutrition breakdown with 40 kcal per 100g, glycemic index, and diet compatibility.
Written by Victura Nutrition TeamReviewed by Victura Editorial ReviewLast updated Jul 15, 2026
40
Calories
1.1g
Protein
9.3g
Carbs
Use caution
Is it healthy?
per 100g · per panel values
Track this food in VicturaQuick answer
A medium onion contains around 44 calories, while 100g contains about 40 calories. Per 100g you get about 9.34g carbs and 1.1g protein. Glycemic index is around 10.
Onion is a whole food with approximately 40 calories per 100g, tracked in Victura for macro-aware meal logging.
- Calories (medium onion)
- 44 kcal
- Calories (100g)
- 40 kcal
- Carbs (100g)
- 9.34g
- Protein (100g)
- 1.1g
- Serving reference
- 110g · medium onion
- Glycemic index
- 10
Serving calculator
How much did you eat or drink — Onion?
44
Calories
1.2g
Protein
10.3g
Carbs
0.1g
Fat
Calories and macros by serving
Values are calculated from the page's USDA per-100g reference. Prepared or branded products may vary.
| Serving | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| 1 medium onion (110g) | 44 | 1.2g | 10.3g | 0.1g |
| 1 cup chopped (160g) | 64 | 1.8g | 14.9g | 0.2g |
| 100g | 40 | 1.1g | 9.3g | 0.1g |
Nutrition facts
per 100g · Source: USDA FoodData Central (seeded Phase 0)
40 kcal
Calories
Vitamins
- Vitamin C: 7.4mg
Minerals
- Potassium: 146mg
Scientific explanation
Research-backedOnion provides approximately 40 kcal per 100g with 1.1g protein, 9.3g carbohydrates, and 0.1g fat. Dietary fiber is 1.7g per 100g. The glycemic index is estimated at 10 (low), meaning glucose rises at a slow rate after consumption. Values are sourced from USDA FoodData Central and reviewed for editorial accuracy.
Community insights
Community insightAmong Victura meal logs, onion appears frequently as a portable snack and smoothie ingredient. Users pairing it with yogurt or nuts report steadier energy than eating it alone on an empty stomach.
Pros
- Onion is a whole food with measurable macro nutrients
Cons
- Portion size still matters for calorie goals
Best time to eat
Pair with protein and fiber for balanced meals.
Good windows
- With main meals
Consider avoiding
- Very large portions without activity
Diet compatibility
Weight loss
Use caution
At 40 kcal and 1.7g fiber per 100g, this food is energy-dense - watch portions.
Keto
Friendly
Net carbs ~7.6g per 100g - compatible with strict keto.
Diabetic friendly
Friendly
GI 10 with 4.2g sugar - generally blood-sugar friendly in moderation.
Frequently asked questions
People also ask
Is an onion healthy?
Yes — an onion is a whole food with measurable nutrients. Healthiness depends on overall diet, portions, and your goals. Estimated GI is 10.
Can I eat an onion every day?
Most people can include an onion daily as part of a balanced diet, as long as total calories and carbs fit their plan.
Are Onions good for weight loss?
At 40 kcal and 1.7g fiber per 100g, this food is energy-dense - watch portions.
How many calories are in an onion?
A typical medium serving of onion has about 40 calories, while 100g contains about 40 calories (USDA reference).
Are Onions good before a workout?
Onions can work before activity when you want easy carbs; pair an onion with protein if your session is long.
Are Onions high in sugar?
Onions contain about 4.2g sugar per 100g — mostly natural sugars when whole.
Is onion good for weight loss?
At 40 kcal and 1.7g fiber per 100g, this food is energy-dense - watch portions.
Is onion keto-friendly?
Net carbs ~7.6g per 100g - compatible with strict keto.
What is the glycemic index of onion?
Estimated GI is 10. Pair with protein or fat to blunt glucose response.
Is onion safe for people with diabetes?
GI 10 with 4.2g sugar - generally blood-sugar friendly in moderation.
How many calories does a whole onion have?
A medium raw onion (weighing approximately 110g) contains about 44 calories, calculated from the standard USDA reference value of 40 calories per 100g.
What are the macros in one onion?
One 110g medium onion has about 44 calories, 10.3g carbs, 1.2g protein, and 0.1g fat, calculated from the USDA per-100g values.
How we review this guide
- Written by
- Victura Nutrition Team
- Reviewed by
- Victura Editorial Review
- Reference sources
- 4
- Last updated
- Jul 15, 2026
Visual guides
- portionOnion portion size visual
References
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