SPF 50 protects you 50 times longer in the sun, so you don't need to reapply it all day, right? Wrong.
The SPF system is calculated this way, but the truth is a lot more complicated. First of all, if you burn easily (like within 10 minutes of being in strong direct sunlight), even a high factor like 30 is only going to give you five hours of protection. But that's just the beginning. The calculation of an SPF is based off a heavy application of thick product in a lab setting, not the quick three-minute rub down most of us give ourselves. It doesn't take into account sweating, swimming, clothing rubbing against the product, or other factors that reduce protection as the day goes by. To add more fuel to the fire, in tests, some big brand sun care products have been proven to have a lower SPF than the label suggests.
For maximum protection from harmful rays, sun protection should be reapplied every 2 hours, more often if you have skin that burns easily. Always use a high SPF, even if you tan easily: sun cream protects from more than just sunburn.
Image Source: POPSUGAR Photography / Sheila Gim