A sun factor 15 SPF 15 blocks 93% of UVB radiation and is the lowest SPF that should be used during exposure to the sun.
Sun protection factor SPF 30 will block 97% of UVB rays. This is the minimum factor advised for children.
Sun protection factor SPF 50 will block 98% of UVB rays. An SPF 50 gives you 50 times more protection of what your skin naturally provides.
Sun protection factor(SPF) 50+ is the highest spf available. An SPF 50+ sun protection is ideal for children and those who's skin is sun sensitive.