What does 30 plus mean in sun screen?

Answer 1

Roughly you are 30 times more protected with that sunscreen than without it. Some think of it as being able to be in the sun 30 times longer without burning than without. They can be in the sun 5 minutes before burning so with 30+ SPF, they can be in the sun 150 minutes ( 2.5 hours) before burning. Not true. Sunscreen breaks down as you wear it, the same way make-up fades from your face. The longer you go between applications of sunscreen, the more likely you are to burn. Reapply per the manufacture's directions, and more often if you sweat and after drying off. Just like foundation, when you sweat or touch your face, it comes off. 30+SPF is the Spectral(Sun) Protection Factor, not Spectral Burn Proof Factor ;)