A standardized cup is around 240ml. Once you know that you should be able to tell if a cup roughly fits that requirement. Or you just get one designed for baking. Just as widely available as kitchen scales. Or you keep weighing your food. I don’t know what else to tell you.
And as long as you keep track of which of your 5 different cups is the one that’s 16 times larger than the tablespoon measuring scoop. :)
A standardized cup is around 240ml. Once you know that you should be able to tell if a cup roughly fits that requirement. Or you just get one designed for baking. Just as widely available as kitchen scales. Or you keep weighing your food. I don’t know what else to tell you.