Girls. How do I properly prepare formula?

Girls. How do I properly prepare formula? I took 120ml of water and add the formula, it turns out to be 130 or more ??‍♀️ Is that how it should be? Or do I need to take less water first and then add it up to 120? In the instructions, you first need to pour in the water exactly then add the formula. But it turns out to be more.