SPF stands for Sun Protection Factor. To determine what level of SPF that you need in your sunscreen, you need to examine what your usage will be for. Typically, for long days out in the sun where there will be a lot of swimming or sweating, it’s ideal to wear an SPF of 30 or higher and reapply at least every 2 hours. If you know that you are exceptionally sensitive to getting sunburns, it may be in your best interest to purchase sunscreens that are SPF 50 and/or apply more frequently.