Ask a Dermatologist: Dr. Shereene Idriss on All Things SPF
SPF number matters…a lot! On average, SPF 15 offers 94% protection whereas SPF 50 offers 98%. At 94% protection, your skin is still exposed to 6% of UV rays, whereas at 98% protection, only 2% of those rays make it through. That’s nearly a 70% increase in protection! So although a 4% increase in SPF may not seem significant at first, it is in fact a huge amount.