Sunscreens with an SPF greater than 30 are not more beneficial than SPF 30.
More sunscreen manufacturers are coming out with versions that have an SPF of 45, 50, even 60. But there's controversy about whether products with an SPF greater than 30 offer any advantages.
An SPF of 15 blocks out 93% of UVB rays, while an SPF of 30 blocks out more than 96%. But higher values provide only an incremental benefit. For example, increasing the SPF from 30 to 40 increases UVB protection less than 1%...but may require 25% more active ingredients. These products usually cost more and may increase the risk for adverse effects.
Dermatologists recommend at least an SPF 15 sunscreen for most people. And for those who are more sensitive to the sun, an SPF of 30 should suffice.