Is Red onion keto?
Red onion is keto only in small portions: it has ~5 g of net carbs per 1/2 medium onion, against the keto diet's 5 g-per-serving limit.
Net carbs = total − fiber
5 g
per 1/2 medium onion
These are the carbs that count on keto: total carbs minus fiber.
Red onion contains 5.3g of net carbs per serving, which is moderate for a ketogenic diet.
Nutrition facts for red onion
How many carbs are in red onion?
Red onion has ~6 g of carbs and ~5 g of net carbs per 1/2 medium onion (total carbs minus 1 g of fiber).
Why red onion is keto only in small portions?
On keto the goal is to stay under ~5 g of net carbs per serving; red onion has 5 g per 1/2 medium onion (6 g total − 1 g of fiber).
How much red onion can I eat on keto?
To stay under 5 g of net carbs, the limit is ~66 g of red onion.
Related
In moderation
In moderation
Yes
Yes
No
No
Keto recipes with red onion
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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