By Fingers
This is the easiest and most likely used. You will hardly carry a syringe or measuring spoon in your beach bag, but you can easily gauge the amount of sunscreen you are applying to your face by using your hands.
Ilyas explains that “the fingertip unit is the unit we use as our unit of measurement” to get the right amount of .04 ounces. She further says that, when you look at the first crease in your fingertip right down to the fingertip. That’s generally two pea-size amounts, which is the amount of product you need on your face.