it should say on the nutrition label. mine is 14g per Tablespoon or 4.6 repeating per teaspoon. but my butter also runs high or low [i can't remember which, just that i have to use my manually entered info, not the generic]. even if your butter is a little off, that should be the general area.
also, if you are measuring by teaspoons and Tablespoons, why not enter in the nutritional info for your butter so you can weigh it and enter it in the same way?