If you're planning on spending a few afternoons at the beach this summer, then you'd be wise to head to the pharmacy to pick out some new sunscreen. Most people reach for the highest SPF they can find - but are you really more protected as the numbers get higher?

SPF stands for " sun protection factor"  and it indicates how long a certain type of sunscreen will keep you protected from harmful UV rays. SPFs range from 4 (for the very brave or very dark) all the way up to 75 and beyond. Which SPF is the best one if you're looking to get a healthy tan while shielding your skin from damage? You can typically stay in the sun for 30 minutes before you begin to burn, but with an SPF of 4, you can stay out 4 times longer - so 120 minutes, or two hours. With an SPF of 15, you could stay out for 30 minutes times 15, or 450 minutes or 7.5 hours.

So, a higher SPF doesn't mean higher protection - it means longer-lasting protection. If you're fair, you're just as protected applying SPF 15 sunscreen often as you are applying SPF 75 sunscreen once. In fact, we actually recommend a lower SPF - between 25 and 45 is probably ideal - so that you'll remember to apply it more often. Even a high SPF can rub off when you sweat, hop in the water or put on your clothes, so you may actually be more protected applying a low SPF often than a high SPF once.So when you hit the beach this summer, don't forget the sunscreen - no matter what SPF you pick!