When the summer sun is blaring down and you need a little protection for your scalp, face, lips, and body, you might assume that a higher SPF is the surest way to prevent a scorching sunburn. (There’s a reason your parents weren’t keen on that SPF 8 you swore by as a teen, right?)

So… is SPF 100, or high SPF in general, really more effective? Yes—and no.