Know Your Numbers
A sunscreen with an SPF of 15 filters out about 93 per cent of cancer-causing UVB rays, while an SPF of 30 protects against 97 per cent of them. SPF 50 stops 98 per cent, and SPF 100 stops 99 per cent. So the higher the SPF, the more marginal the difference—and no sunscreen is able to protect you from all UVB rays.
Looking for other ways to protect your skin? Check out these 10 Foods That Boost Your Skin’s SPF.