An SPF of 30 or greater is recommended for adequate sun protection because real-world application is typically half the amount used in SPF testing.

“you're looking for a number above 30 why why 30 because every study that looked at defining the SPF required you to put a certain amount on the skin generally it's an entire shock glass worth of the product on sun Exposed Skin most of the time in real world uh practice people don't put on that much they put on maybe half that so what you're really getting when you buy something that's SPF 15 is like an SPF of eight so if you're looking for something that provides protection SPF 30 or greater”