Chronometer says 1 cup of onion is 15.3 g carbs. A medium 2-1/2" onion is 8.7 g.
But some people on this forum want to stay in ketosis (I never cared about it, I just want to feel right and reach my goals) and it’s very easy to mess it up with onions if you ask me. Onions are very carby and some people eat them galore.
I was a big fan too but I went over my 40g net carb limit for keto with fried cauliflowers in no time as well and had to ban cauliflowers… And I needed a bunch of carbs for my other items.
Calorie King’s cup is 120grams = 5.5 g carbs
Google’ cup is 160g = 15 g carbs
Fitbit’s cup is160g = 16g carbs
It seems Calorie King’s carbs are out. Calorie King was recommended by my husband’s diabetes educator. This isn’t good as that’s what we’ve been following.
My data says 8g (net?) carbs for 100g onions.
Reality is obviously not that fixed, plants are like that, one is more watery, one is more sugary but it’s good enough for me. They even taste similarly sweet! Would I eat half-ripe pumpkins or pears (or even some unknown, not so sweet apple), I would be totally clueless.
Chronometer agrees with your source - 100 g = 8 g carbs net