I would usually measure based on the combined total of cereal+breastmilk/formula, if that makes sense? So I'm not sure if 2tbsp cereal + 2oz liquid = exactly 3oz, but whatever it is combined should be measurable in tbsp or oz. If you want to give a total of 1oz cereal with milk, then mix it first and the measure out 1oz (or 2, or 3, or whatever you are going for). HTH