Is Higher SPF Always Better? SPF 30 vs 50 vs 100
Reaching for the SPF 100 bottle feels safest, but dermatologists explain why the number alone can mislead you.
Moving from SPF 30 (blocks ~97% of UVB) to SPF 50 (~98%) adds only about one percentage point of protection, and higher-SPF products neither last longer nor remove the need to reapply.
Dermatologists generally recommend SPF in the 30 to 50 range, explaining that the extra margin helps compensate for the fact that most people apply far less sunscreen than the amount used in lab testing.
Questions we get a lot
Does SPF 100 protect twice as well as SPF 50?
No. SPF 50 blocks about 98% of UVB and SPF 100 blocks only a fraction of a percentage point more. The protection curve flattens sharply at the high end, so doubling the number does not double the protection. Dermatologists generally consider SPF 30 to 50 sufficient when applied correctly.
Does a higher SPF mean I can skip reapplying?
No. SPF measures how much UVB is filtered, not how long protection lasts. A high-SPF sunscreen still breaks down with sweat, water, and time, so you must reapply roughly every two hours and after swimming or toweling off. The Skin Cancer Foundation stresses reapplication regardless of the number on the bottle.
r/30PlusSkinCare: 'Is there any real point to SPF 100, or am I just paying more for a bigger number on the bottle?'