Onion is keto: it has ~4 g of net carbs per 1/2 medium onion, within the keto diet's 5 g-per-serving limit.
Net carbs
4 g
per 1/2 medium onion
These are the carbs that count on keto: total carbs minus fiber.
Half a medium onion has about 4.3 g of net carbs, making it fine in moderate portions on keto.
Nutrition facts for onion
0.1 g
Fat
0.6 g
Protein
0.9 g
Fiber
Why onion is keto?
On keto the goal is to stay under ~5 g of net carbs per serving; onion has 4 g per 1/2 medium onion (5 g total − 0 g of fiber).
How much onion can I eat on keto?
To stay under 5 g of net carbs, the limit is ~64 g of onion.
Related
✕No
Corn
18 g net
/ 1 medium ear
✓Yes
Cabbage
3 g net
/ 1 cup, chopped
✓Yes
Broccoli
3 g net
/ 1 cup chopped
✓Yes
Green bean
4 g net
/ 1 cup
✓Yes
Mushroom
1 g net
/ 1 cup, sliced
✕No
Butternut squash
13 g net
/ 1 cup, cubed
See all: Verduras keto
Source: nutritional estimate (USDA-style reference) · Confidence: high
Reviewed by the Ketorai team · Last updated: July 1, 2026 · How we assign the verdict
For information only. This does not replace advice from a health professional.
Reviewed by the Ketorai team · Last updated: July 1, 2026 · How we assign the verdict
For information only. This does not replace advice from a health professional.
Something off? Let us know.
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