What is the highest sun protection factor (spf) you can find in stores, that is still a meaningful SPF number?

SPF. The highest spf sunscreen available is spf 100, but this is not any more effective than spf 50. Spf 50 is about the original base of how high an spf can go and still be logical.
50 SPF. 50 spf is really the highest useful sun protection factor. The fda will soon cap the maximum spf at 50.