Carbs in Onion
Keto-friendlyOnion (per 100 g) contains 9.4g total carbs, 7.7g net carbs, 0.1g fat, 1.1g protein, and 40 calories.
Last updated June 10, 2026 · Reviewed by Jordan Lee, RD, Registered Dietitian
7.7g
Net carbs
9.4g
Total carbs
1.7g
Fiber
1.1g
Protein
0.1g
Fat
40
Calories
Values per 100 g.
Carbs by serving size
| Serving | Net carbs | Total carbs | Protein | Calories |
|---|---|---|---|---|
| 1 medium onion | 8.5g | 10.3g | 1.2g | 44 |
| 100 g (3.5 oz) | 7.7g | 9.4g | 1.1g | 40 |
| 1 oz (28 g) | 2.2g | 2.6g | 0.3g | 11 |
Nutrition facts
| Nutrient | Amount (per 100 g) |
|---|---|
| Calories | 40 |
| Total carbs | 9.4g |
| Net carbs | 7.7g |
| Fiber | 1.7g |
| Sugar | 4.4g |
| Sugar alcohols | 0g |
| Protein | 1.1g |
| Fat | 0.1g |
| Sodium | 4mg |
| Potassium | 0mg |
Source: Open Food Facts (USDAHouston Food Bank). Net carbs = total carbs − fiber − sugar alcohols, computed by CarbMeNot.
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Frequently asked questions
- How many carbs are in onion?
- Onion has 9.4g of total carbs and 7.7g of net carbs per 100 grams.
- How many net carbs are in onion?
- Onion has 7.7g of net carbs per 100 grams (total carbs 9.4g minus 1.7g fiber).
- Is onion keto-friendly?
- Yes — with 7.7g net carbs per 100g, onion fits a ketogenic diet in normal portions.
- How many calories are in onion?
- Onion has 40 calories per 100 grams.
- How many carbs are in 1 medium onion of onion?
- 1 medium onion of onion (110g) has about 8.5g net carbs, 10.3g total carbs, and 44 calories.
