Confusion about net carbs in chia, hemp, and flax

Hi all, I have a question if you don't mind:  I see a lot of conflicting nutrition data on chia, hemp, and flax seeds on the internet in regards to net carbs.  For example, "BetterBody" chia seeds on Amazon lists chia seeds as 3 net carbs for 2.5 tbsp, however a quick Google Image search for "chia seeds nutrition info" lists chia seeds as often having no net carbs at all.  My question is, do net carbs for seeds change based on the brand or manufacturer, or are some of them just simply wrong, or are some just "rounding" numbers incorrectly?  What websites does everyone trust around here for absolutely accurate net carb calculations?  Thanks so much!