How many carbs in baking powder?

Baking powder typically contains a negligible amount of carbohydrates, usually around 1 gram or less per teaspoon. It's primarily a leavening agent made from a combination of an acid (like cream of tartar) and a base (like baking soda), along with a starch to keep it dry. The starch may contribute some carbohydrates, but the amount is minimal in the context of a typical recipe.