This is a number, also called “sun protection factor” that measures the amount of sun protection conveyed by a sunscreen. As the SPF increases above 30, the amount of sun protection provided by the sunscreen decreases very rapidly. For this reason, the US FDA will no longer permit labeling of sunscreens with SPFs greater than 50. The American Academy of Dermatology recommends a sunscreen with an SPF of at least 30.