Is Onion keto?
Onion is keto only in small portions: it has ~7 g of net carbs per 1/2 cup chopped, against the keto diet's 5 g-per-serving limit.
Net carbs = total − fiber
7 g
per 1/2 cup chopped
These are the carbs that count on keto: total carbs minus fiber.
Onions are moderate for keto with 7.3 grams of net carbs per serving.
Nutrition facts for onion
How many carbs are in onion?
Onion has ~8 g of carbs and ~7 g of net carbs per 1/2 cup chopped (total carbs minus 1 g of fiber).
Why onion is keto only in small portions?
On keto the goal is to stay under ~5 g of net carbs per serving; onion has 7 g per 1/2 cup chopped (8 g total − 1 g of fiber).
How much onion can I eat on keto?
To stay under 5 g of net carbs, the limit is ~55 g of onion.
Related
In moderation
In moderation
Yes
Yes
No
No
Keto recipes with onion
✓ Keto-friendly
✓ Keto-friendly
✓ Keto-friendly
See all: Keto vegetables
Reviewed by the Ketorai team · Last updated: July 5, 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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