How much SPF is enough?
The simple logic behind wearing sun cream is this: You apply it, you prevent sunburn. But if you glance at any two sunscreen labels, youll instantly understand that no two formulas are alike when you start incorporating things like UVA/UVB/Broad Spectrum, PA++++, SPF, mineral vs chemical, and so forth, it can get a little convoluted. (To say nothing of how it actually feels on your skin, and whether it's actually waterproof, and whether it makes you look like an out-of-work mime.) So heres a general explainer on how to read a sunscreen label to know exactly what youre getting from any SPF bottle before you get some sun this summer. What SPF Means  SPF stands for Sun Protection Factor. The numbers associated with SPF are meant to indicate to the amount of time you can be in the sun while wearing that formula (as opposed to being out sans any coverage) and avoid burning. So a proper layer of SPF 15 would shield you 15 times longer than if you had no SPF at all. But heres where those numbers grow confusing: Sure, SPF 30 supposedly covers you twice as long as SPF 15, but that doesnt have anything to do with how long the stuff stays on your skin in practice. The maximum amount of time you should go between reapplications is 2 hoursor after toweling off post-swim or sweat. In practice, SPFs effectiveness wanes quickly, no matter how strong it is from the start.