How much sunscreen should I use on my face?

Use a quarter teaspoon of sunscreen on your face — that’s about two finger-lengths of product or the size of a nickel. SPF ratings are tested at 2 mg per square centimeter, and using less drops protection fast (e.g., SPF 50 becomes closer to SPF 15-20). Dot it all over your face first, then blend, or use a measuring spoon once to train your eye.